In this paper Imam Muhammad Shirazi addresses the issue of non-violence as prescribed in the teachings of Islam; that violence is severely condemned and non-violence is encouraged. The author then goes on to classify violence, and non-violence, into three categories. The author shows how non-violence produces the desired results in all aspects of life, and it is therefore incumbent for all Islamic reform movements to adhere to non-violence if they want to achieve reforms in their societies successfully.
This paper is an extract from Imam Shirazi's book, The Islamic Government, pp 66-88, volume 102 of the "Al-Fiqh series.
One of the most important principles that the forthcoming Islamic government, as well as the Islamic movement, must adhere to is the condition of non-violence. A substantial body of the holy tradition and reports condemns violence as may be found in “The Shi'a Guide to Shari'ah (Islamic Law)”  and “Supplement to The Shi'a Guide to the Shari'ah”  . It is also reported that “Violence is also part of the army of ignorance”. Furthermore, there is equally substantial evidence in the holy traditions and reports encouraging and promoting non-violence, leniency and kindness.
I would add: It is evident from the above quote that the Muslims did not have a sense of vengeance against their oppressors, as taught by the Messenger of Allah (pbuh). This was the kind of behaviour and attitude the Messenger of Allah (pbuh) had shown towards his enemies whether during war times or any other times. For the benefit of the reader some of the reports are presented here.
In a tradition it is reported that Imam Saadiq (pbuh) said:
"Before dispatching a squadron, the Messenger of Allah (pbuh) used to call everyone involved to a meeting and brief them about their duties and responsibilities saying: "Advance in the name of Allah, by the name of Allah, in the cause of Allah and in accordance with the religion of the Messenger of Allah (pbuh). . . . Do not handcuff or tie up (the prisoners), Do not mutilate, Do not use treacherous means (with the enemy), Do not kill the old, Nor the young, Nor the women, Do not cut down the trees; unless you are forced to do so. If any of the Muslims, whether high ranking or otherwise, give temporary refuge to any of the infidels to hear the message of Allah (to accept Islam), (let him do so). If he follows you, (i.e. accepted Islam) then he is your brother in religion, and if he refuses, secure his safety, and seek help from Allah.""
In another tradition, Imam Saadiq (pbuh) is also quoted as saying:
"Before their mission the Messenger of Allah (pbuh) used to order the squadron leader in particular, and the whole company in general, to fear Allah. The Messenger of Allah (pbuh) then used to say to them: "Advance in the name of Allah and in the way of Allah. Fight any system who denies Allah, Do not use treacherous mean (with the enemy), do not handcuff or tie up (the prisoners), do not mutilate, do not kill the young, nor he who has sought refuge to the peak of the mountain, do not burn the palm trees, nor flood them, do not cut down fruit-bearing trees, do not burn the crops, you may even need them, do not kill the animals except those you need to eat. Then when you meet the enemies of the Muslims invite them to one of three. If they respond (positively) to these, accept (their response) and stay your hands from them. 1. Invite them to Islam, and if they enter Islam accept it from them and stay your hands. 2. Invite them to emigrate (to Islamic cities  ) after they have accepted Islam. If they do, accept it from them and refrain from any measures against them, and if they refuse to emigrate to such centres, they will be treated like any other Bedouin faithful; they will not qualify for Fay' and Qassma  rewards unless they emigrate in the cause of Allah. 3. If they refuse these two options, invite them to pay tribute submissively  . If they agreed to pay tribute, accept it from them, and if they refuse, then seek assistance from Allah the Almighty against them."
While addressing the people in (preparation for the battle of) Siffeen, Amir-ol-Mo'meneen (pbuh) said,
"Allah the Almighty has shown you a trade which delivers you from painful punishment and guides to the good; (That is) belief in Allah and struggle in the cause of Allah. He has made his reward the forgiveness of sin and beautiful dwellings in the heavens. The Almighty said: "Allah loves those who fight in His cause arrayed in battle, as though they were a compact structure." So make your arrays like compact structures. Amir-ol-Mo'meneen continued until he said: "Do not mutilate the dead, and if you overwhelm the enemy do not violate their properties (i.e. respect their privacy), Do not enter a house, do not take anything from their property (belongings) except what you find in their barracks. Do not agitate any woman, even if they swear at you or insult your leaders or your reverend people. For they lack the maximum physical, psychological or mental strength. We used to be instructed to refrain (from causing harm to them) even when they were idolaters. Even (at that time) if a man hit a woman he would have been rebuked and ridiculed by others (and branded as coward for using force against the weaker sex) as well as his sons.
After the battle of the ‘Camel' was started and headed by A'ishah against Amir-ul-Mu'minien Imam Ali (pbuh), during which A'ishah and her army were defeated, Imam Ali (pbuh) announced:
"Do not kill the injured, Do not pursue those fleeing, Whoever puts down his weapon is safe (from being attacked)."
Imam Ali then rode on the mule of the Messenger of Allah and called a number of individuals by name. Some 60 elders, all of whom were from the Hamdaan tribe, gathered around him wearing their protective helms, swords and shields. They followed Imam Ali until he reached a big house. He asked for the door to be opened. Once inside Amir-ol-Mo'meneen saw women wailing and weeping. When they saw Imam Ali (pbuh) they all shouted with one voice: He is the killer of our beloveds. Imam Ali did not say anything to them. He only asked for A'ishah's apartment. When Imam Ali entered her room, their conversation could be heard. A'ishah was apologising to Imam Ali. As Imam Ali left the room he saw a woman who he recognised and said to her: If I were the killer of the loved ones I would have killed those in this room, and in this room, and in this room, pointing to three different rooms. The woman, Safeyyah, went to the wailing women to convey what Imam Ali had said. Then they all ceased wailing. Al-Asbagh, the narrator of this report, said: In one of the three rooms was A'eshah and her entourage, in the second was Marwaan ibn al-Hakam and the youths of Quraysh, and the in the third Abdullah ibn al-Zubair and his relatives resided. Al-Asbagh was asked; “Why did you not arrest them? Were they not the cause of this conspiracy and the war? Why did you leave them free?” Al-Asbagh replied: “We had reached for our swords, with our eyes focused on him (Imam Ali, pbuh), awaiting his command . . . but he did not issue any order except a general amnesty.”
There are countless cases like this, but we only mentioned the above few cases to hint at this point that it is imperative for the Islamic government, and the Islamic movement before that, to adhere to non-violence, even when in power.
Just as violence is a weapon, non-violence is a weapon too. However, the weapon of non-violence is sharper than the weapon of violence. Just as the soul is stronger than the body, so too is non-violence, since it is the weapon of the soul, and so it is more powerful than the weapon of the body which is made of matter. For this reason, the non-violence of the prophet Abraham (pbuh) defeated King Nimrod's violence, and Moses' non-violence defeated Pharaoh's violence, and Jesus' non-violence defeated Herod's violence, and the non-violence of the Messenger of Allah (pbuh) defeated the violence of the pagans' great knights.
If an individual is able to use the weapon of non-violence then it is inevitable that his adversary would succumb to him no matter how strong or ferocious his enemy may be. So we see that Jesus (pbuh) ordered his followers to offer the right cheek of their face to he who slaps them on the left. In doing so he does not want to encourage the offender but he wants to draw the offender to the territory of justice and virtue. Since such a reaction would create a powerful storm in the soul of the offender in sympathy with the victim, which in turn leads the oppressor to be humble before the oppressed. What a transcendental wisdom it is that one can sustain a continuous and satisfactory victory by enduring a little suffering and attract the intelligent foe to one's principles.
In the book "Towards Islamic System of Government" I have discussed this issue as follows:
Non-violence is the third stand upon which the Islamic movement bases its call for an Islamic government, and this is of utmost importance. Non-violence requires a very strong and resilient character, which can withstand any assault with total tolerance, and without retaliating, even if the opportunity is there to do so.
Non-violence is manifested in the hand, in the tongue, and in the heart. Each is easier than the other. Non-violence of the hand is easier than that of the tongue and non-violence of the tongue is easier than that of the heart.
The meaning of non-violence is that an individual puts things right, whether constructive or destructive, with total leniency so that no one is harmed by this cure. It is in fact like the Balsam that is placed on an aching part of the body so that it is healed.
- As for physical non-violence, it is that an individual would not attempt to hurt another individual even with respect to the strongest of his adversaries and even if had the right to do so.
Allah the Almighty states: “and if you forgive, it is closest to righteousness”  .
Therefore one should not slap back his adversary if he did, and should not strike back if he did so, or use any tool or weapon in response. Of course, non-violence does not mean not protecting one's body from an incoming assault. This is self-defence and not violence, and self-defence is part of non-violence. This physical non-violence is a definite necessity for one who has no other means of ensuring the success of his mission.
In fact this was the approach of every great reformer or any intellectual aiming at a particular goal or principle. According to the teachings of Jesus (a), as well as the teachings of the infallible imams (a), one should not return a slap with a slap; but if slapped on the right cheek, one should be ready to receive another on the left. Some might say that this may encourage the offender. The reply (to this argument) would be that this will deter him. Do you see what reaction this response creates in the offender himself? Imagine that you hit someone and in response to this action, and with total tolerance, he says to you that you can hit him again if you wish. Imagine what psychological reaction would result. For anyone who is doubtful about this great wisdom, needs to go no further than to consider the state of Jesus (pbuh) who was surrounded by his adversaries while he had no option but to pursue his mission. Furthermore, what do you say about the Messenger of Allah, Muhammad (pbuh)? Did he want to harm the people of Makkah? History bears witness that the Messenger of Allah (pbuh) used to fully tolerate all the insults and deplorable treatments at the hands of his opponents. Abu Lahab used to pour sheep's fat on the Prophet's head while he was praying; another infidel spits in his face; another used to throw filth into his food. On one occasion, Abu Jahl's slave fractured the prophet's head with a bow; and another; and another; . . . After all this the Messenger of Allah (pbuh) used to pray for these people saying "O Allah, guide my people for they are ignorant."
And this is how Noah, Lot, Abraham, and Ismael (pbuh) were. Have you ever heard that Noah raised his hand to hit back at he who had beaten him unconscious? Or have you seen anywhere in the pages of history books that Lot responded to his people's aggression with aggression? Or that Abraham hit back in response to his uncle's attack? Or that Ismael raised his hand to hit back at he who sliced off some of his scalp? This is none other than because their mission required the adoption of a non-violent approach, the first and most immediate manifestation of which is physical.
The physical non-violence is a weapon that attracts the hearts and minds to he who advocates it, and incites the people against his adversaries. Imagine that you see someone hitting another person but the latter does not respond likewise. Who would your sympathies lie with? Siding with the oppressed is a universal reality that the great reformers have adopted in order to achieve their ultimate goal, which is reform.
Ghandi, one of the activists in the liberation of India, used to say: "I learnt from Imam Hussain (pbuh) how to attain victory while being oppressed."
Not responding to an aggression on the reformer's side not only creates sympathy in the hearts of all other people, but it also brings about compassion in the heart of the aggressor. When someone assaults an individual and the aggressor does not see a similar response from his victim, his heart will be filled with mercy and leniency after being filled with anger and violence.
The invitation (to Islam) needs peace extensively, specially if superpowers opposed their call, whereas the movement possesses nothing but the truth.
Consider if an individual, who is armed with a sword, slaps an activist. If the latter were to respond in a similar manner, what is there to prevent the aggressor from using his sword to attack the activist? Which of the two scenarios are more desirable? To tolerate an assault in order to save his life and his mission, or to return the assault and lose his life and fail his mission?
Therefore we see that the Messenger of Allah (pbuh) used to exemplify Bilaal, Sumayyah, Ammar, and others who tolerated numerous assaults from the pagans. This is not because it is wrong to return aggression, but since to return aggression for a man with a mission would defeat its cause. Therefore when Islam resorted to force, this was to prevent chaos and aggression, even though it normally offered forgiveness on many occasions when deemed not harmful. It has been mentioned previously that this (forgiveness) is based on the question of priorities. Suppose that you are in dispute with an aggressive opponent who has taken over your house. If he assaults you and you know that if you respond similarly, you would lose your argument against him and with that the possibility of getting back your house. Would it not be more prudent to keep your nerve and deal with him rationally rather than returning his assault with an assault? Rational reasoning would certainly opt for the former. This is the common ground between the verses:
“There is no coercion in religion”  and
“(This is) A declaration of immunity from Allah and His Messenger, to those of the Pagans with whom you have made treaties.”  as well as other verses concerning fighting.
When a system-of-belief (religion) does not possess power or it aims to progress (to spread its message) then it would be absurd if it were to compel anyone to accept that belief, as this will bring about its prompt failure. On the other hand if it possessed power or it were preoccupied with important issues, then it would also be absurd to ignore those who engage and encourage corruption and tyranny.
- As for verbal non-violence, it is far more difficult to manage than the physical non-violence. Therefore it can be seen in many cases that someone is not prepared to hit anyone or to assault him physically but he is prepared to assault him verbally and slander him. This is because often verbal (assault) is less prone to prosecution in this world, for the culprit to fear the outcome, and therefore the tongue is free to say anything unchecked. Fearing the consequences, the hand is tied since it is subject to more control then the tongue. More often than not, an individual verbally criticises the ruling regime endlessly but when in detention he receives the beatings, he does not return the assault. Needless to say, there is a difference between non-violence on principle and for the protection of belief and mission, and that of fearing more violence and assault. The latter is the condition of any weak individual in the claws of a powerful one, with the exception that only the weak individual would respond if he loses his rational reasoning, since no one in their right mind would do anything to cause himself more harm. Whereas the former is a spiritual virtue which an individual uses to save his mission and not out of fear of punishment. A non-violent individual will have a stronger character; a more composed, and in control of his conduct and has higher moral value and conscience than the aggressor.
In any case, verbal non-violence is to curb one's tongue and check one's words in order to make sure one's words do not damage the aggressor, whether his aggression was physical or verbal.
This kind of non-violence is a great virtue and it is imperative that those involved in the invitation to (Islam) practice it however rough a ride it may prove to be and however difficult it may be to control. The strongest of all those who respond likewise to aggression is he who, when faced with a barrage of insults and accusation, seeks refuge in silence and abstains from responding likewise, in the interest of the cause and progress of Islam.
Allah states in the holy Qur'an:
"Respond with that which is better, so that he, between whom and you there was animosity, shall be like an intimate friend. And none shall be accorded this rank except those who have stood fast, and none shall be accorded it except one blessed with great good fortune." 
Such a fortune is called a 'great fortune' by the Lord of existence. Otherwise how can an individual respond to insult with praise (for the offending individual concerned), and to slander with commendation, and to belittlement with extolment, except if he was an individual who has stood fast, tolerated and persevered. Imam al-Sajjaad (pbuh) in his prayer, known as Makaarem al-Akhlaaq, or the Most Noble of Ethics, says:
"O Lord have Mercy on Muhammad and his descendants . . . and help me to tender with sincerity whoever cheated me, and to reward with kindness whoever abandoned me, and to repay generously whoever denied me, and to recompense by making bond with whoever broke off with me, and to praise whoever backbite against me. Enable me to appreciate the good deed and forgive the bad deed." 
That is, Islam commissions a Muslim, for being a muslim, to give good counsel to he who cheats him, be kind to he who boycotts him, to give generously and extensively to he who denies him, to bond with he who cut him off, to praise he who slanders him. This duty is more so for a Muslim reformer who wants to clean and revive his country from intellectual, military, economical, and cultural tyranny and corruption. He needs this weapon (of non-violence) more than any other person. In fact this is the only weapon for the unarmed who is confronted by those who have armed themselves to the extent that they have drowned themselves in metal, fire, nuclear and Hydrogen bombs.
It is reported that Jesus (pbuh) along with some of his follower came across a group of Jews, the latter insulted Jesus (pbuh). In response to them, Jesus (pbuh) praised them. His followers said to Jesus, "O Spirit of Allah! They swear at you and you praise them!?" Jesus (pbuh) replied; "Yes. Every one gives whatever he has." What a great word and magnificent wisdom. He who is filled with insult and filth, nothing comes out of him except swearing and slander. And he who embodies goodness, wisdom, virtue and high moral values, emits nothing but kindness, praise and compassion. Thus was the teaching of the prophets with no difference between Abraham, Moses, Jesus and Muhammad as well as all other prophets (peace be upon them). With such a policy, their calls of reform succeeded and managed to open a way in the material world of position and power and establish themselves for as long as man has existed. When wealth and power have vanished, those teachings remain as the torch of guidance for mankind in the dark world that the tyrant and arrogant powers bring about.
If the prophets were not to arm themselves with the weapon of non-violence, their calls and missions would have been buried in their infancy by the lords of wealth and power. Consider, for example, the well-known story of Imam Hassan (pbuh) when a man from Shaam  came across the Imam and started swearing at and cursing the Imam and his father (a). Imam Hassan (pbuh) did not respond to the man and remained silent until he finished what he had started. When the man stopped his barrage of insults, Imam Hassan addressed the man a smile:
"O' Sheikh! I guess you are a stranger in this territory and you might have mistaken (me). For if you seek contentment from us, we would gratify you, and if you ask us for anything we shall give it to you, if you seek any guidance from us we shall guide you, and if you seek vehicle from us we shall arrange one for you, if you are hungry we shall feed you, if you need any clothes we shall give you them, if you are poor we shall give you money, if you have been expelled (from your hometown) we shall accommodate you, and if you have any need we shall fulfil your need."
On hearing this response from Imam Hassan (pbuh), the man was so ashamed of his behaviour towards the Imam that he broke into tears and said: "I testify that you are Allah's Deputy on this earth, Allah knows best where He places His message  ".
Similar events have been reported in the traditions of the prophets and the infallible Imams (a) where they return insult and aggression with kindness, but are naturally beyond the scope of this brief work.
However we can see the Qur'an puts forward a good framework for a philosophical and practical call to peace and non-violence:
"Invite (all) to the Way of thy Lord with wisdom and beautiful preaching; and argue with them in ways that are best and most gracious." 
"And when the ignorant address them, they say, "Peace!"" 
"Do not dispute with the people of the Book but in the fairest way." 
"And if they turn their backs, say: "Bear witness that we are Muslims" 
"Hold to forgiveness; enjoin the good and turn away from the ignorant." 
"Do not curse those [deities] whom they call upon besides Allah, lest they wrongfully curse Allah without knowledge." 
"It is by a mercy from Allah that you dealt leniently with them; for had you been hard-hearted, they would have dispersed from around you. So pardon them and ask Allah's forgiveness for them." 
"Let them forgive and overlook: do you not wish that Allah should forgive you?" 
- The third category of non-violence is that of the heart, which is the hardest of the three, (non-violence of the hand, tongue and heart)
The meaning of the non-violence of the heart is that one does not fill his heart with violence towards foes and adversaries. And it is normal for what is in the heart to seep through to facial expression, and body language. "One does not intend anything without it reflecting in the slips of his tongue or features of his face.", as stated in a tradition. So one may take care to eradicate physical and verbal non-violence but not of the heart. Depicting such a condition a poet states:
As of the tongue, it is coated with honey
But the hearts (are) wasps and snakes
Furthermore is he who has violence in his heart able to hide his violence forever? Surely no. It is inevitable that his violence will come to the surface, even if under unusual circumstances. Hinting at this aspect, a poet states:
Secret has two windows: drunkenness and fury.
Since keeping what is in the heart hidden forever is normally impossible, according to the poet who states:
No matter what character an individual may have,
If he wanted it hidden from the people, it would (eventually) be found out.
This paper appears in the book
War, Peace, and Non-Violence: an Islamic perspective