The ruling on rejoicing at the killing of some sinners

The answer – and Allah is the One who grants success – is that if the matter is as described, then the one who rejoices at the killing of the one who harms people and insists on harming them does not incur sin. Rather, his killing is a blessing for which the people must give thanks, since Allah has spared them his harm without any effort on their part. Likewise, there is no blame on the believer if he supplicates against sinners who harm the believers, asking for their killing, and then rejoices when Allah answers his supplication.
In sum: there is no blame in rejoicing at the killing of one who disobeys Allah because of his disobedience. The blame and sin lie in rejoicing and being glad at the killing of a believer because of his faith.
If rejoicing and happiness occur at the killing or death of a believer because the one who rejoices will obtain an inheritance from his estate, or will receive wealth from his estate by a bequest, or because the heirs are poor and his estate will enrich them…
I have heard some of my teachers in knowledge say to certain people, jokingly: “My death will be a cause of joy for my heirs, because my death will be a cause of their becoming wealthy; whereas you, there will be no joy in the death of your testator.” This is the gist of his words – may Allah have mercy on him – and he was a scholar and a wealthy man.
If it is said: it has been established that approval (riḍā) of an evil deed is itself an evil deed; the one who is pleased with disbelief is, in ruling, like a disbeliever, and the one who is pleased with the killing of a Muslim is, in ruling, like the killer. Allah punished the people of Ṣāliḥ when they approved of the killing of the she-camel, even though the actual killer of it was only one of them: “But they denied him and hamstrung her; so their Lord crushed them for their sin and levelled them with the ground .” [al-Shams:14]
We say: the people of Ṣāliḥ all wanted to kill the she-camel and resolved upon that, in disobedience to the words of their Prophet Ṣāliḥ (peace and blessings of Allah be upon him) which Allah related in His saying: “This is the she-camel of Allah as a sign for you, so leave her to graze in Allah’s land and do not touch her with harm, lest a painful punishment seize you.” [al-Aʿrāf:73] He, their Prophet (Peace be Upon Him, and May Allah bless him) , warned them against transgressing against the she-camel of Allah and (against transgressing) upon her share of water, forbade them from attempting that, and warned them of Allah’s punishment if they did what he had prohibited them from. But they rebelled against their Prophet Ṣāliḥ (peace be upon him), belittled him, and denied him. They all shared in rebellion, disobedience, and denial, and resolved to oppose him in what he had prohibited them from and warned them about.
Approval (riḍā) is one thing, while joy and happiness are something else. Our Imāms have said: “Riḍā is a word synonymous with ‘will’ (irādah); it is not correct to say, ‘I was pleased with this but did not will it,’ nor, ‘I willed it but was not pleased with it.’ Whoever says that is considered self-contradictory.” This is how they have stated it in the books of the principles of religion.
On this basis, approval (riḍā) is an inward act of the heart for which the legally responsible person is rewarded or punished.
As for joy and happiness (farḥ and surūr), they are a psychological reaction that occurs in the soul upon the occurrence of their cause, and its occurrence is involuntary; the one who rejoices has no choice regarding its occurrence. Rather, it arises in the soul according to its natural disposition.
It has been established in the Sharīʿah that the legally responsible person is not punished for what arises from the natural disposition of the soul, because it is not within his capacity to rid himself of that. It has been related that the following was revealed concerning this: “Allah does not burden any soul beyond its capacity.” [al-Baqarah:286]
We should recognize that it is among the characteristics of a believer that he is distressed by the killing of a believer, and that he rejoices and is gladdened by the killing of the enemies of the believers. If you see a legally responsible person rejoicing at the killing of believers because they are believers, then he is not a believer.
It is also among the characteristics of the believer that he rejoices at the killing of sinful Muslims because of their disobedience to Allah, their rebellion against Him, and their persistence in that; for the believer hates disobedience to Allah and shuns it: “…and has made hateful to you disbelief, wickedness, and disobedience…” [al-Ḥujurāt:7]
If it is said: most sinners do not deserve death with Allah, nor in His law, on account of their sins and persistence in them; rather, they deserve disciplinary punishment (taʾdīb). Therefore, it is not permissible to rejoice and be glad at their being killed with a killing they do not deserve in Allah’s ruling; and there is no doubt about the ugliness of rejoicing and being glad at what contradicts Allah’s ruling.
It is said: the joy and happiness at the killing of the wicked, the harmful, and those who persist in disobedience to Allah is not because of the killing itself, but because of the safety from their evil and harm that is realized through their being killed, and because of the disappearance of disobedience through the death of the disobedient. This is the aspect in which the believer rejoices at their being killed. There is no disagreement about the goodness of rejoicing and being glad at safety from evil and harm and from the disappearance of acts of disobedience.
There is no doubt whatsoever that what motivates the believer’s joy and happiness at the killing of sinners is not the fact that the killing contradicts Allah’s ruling. There is no doubt that rejoicing at the contravention of Allah’s ruling is not among the traits of the believers; rather, it is only among the traits of the disbelievers and the openly sinning.
What has preceded clarifies for us that rejoicing at killing is praiseworthy from one perspective and blameworthy from another.
Moreover, our scholars and others have established in the chapter of commanding right and forbidding wrong that killing sinners is permissible – or even obligatory – if they persist in disobedience and do not desist from it after efforts have been made to remove it by every possible means. If there remains no way to remove the evil except through killing, then killing becomes permissible or obligatory – “and the last of cures is cauterization.” In that case, killing becomes Allah’s ruling concerning those sinners who persist in their disobedience, upon whom gentleness, fear of Allah, and clarification of the proofs and evidences, and neither this nor that, etc., have had no effect.
Allah, exalted is He, has described the killing of the wicked as a victory for His allies, in His saying: “Were it not that Allah repels people, some by means of others, monasteries, churches, synagogues, and mosques in which Allah’s Name is much mentioned would surely have been demolished. And Allah will certainly help those who help His cause. Indeed, Allah is All-Strong, All-Mighty.” [al-Ḥajj:40] And He, exalted is He, has described this as bounty and grace in His saying: “And were it not that Allah repels people, some by means of others, the earth would surely have been corrupted; but Allah is full of grace to all the worlds.” [al-Baqarah:251]
It is among the characteristics of the believers that they rejoice in Allah’s bounty upon them, as He, exalted is He, says: “Say, ‘In the bounty of Allah and in His mercy – in that let them rejoice; it is better than what they accumulate.’” [Yūnus:58]
And it is among their characteristics that they rejoice in Allah’s granting victory to His believing allies, as He, exalted is He, says: “And on that Day the believers will rejoice in the help of Allah. He helps whom He wills, and He is the All-Mighty, the Most Merciful.” [al-Rūm:4–5] So what room is there for any objection against a believer rejoicing in Allah’s bounty and in His granting victory to His allies

Source: Min Thimār al-ʿIlm wa al-Ḥikmah vol.2