KNOW THAT HAVING a bad opinion is as unlawful as backbiting. Just as it is ḥarām to talk to others about the evil of a person, it is ḥarām to talk to yourself about that and to think evil of that person. Allah
says: “Avoid much suspicion.” [1].
We relate in the Ṣaḥīḥs of al-Bukhārī and Muslim that Abū Hurayrah
related that the Messenger of Allah
said: “Beware of suspicion, for suspicion is the most untruthful discourse.” [2].
Hadiths on the above subject are numerous. The general idea of it is that of setting the heart and its passing judgement on the evil of another.
However, fleeting thoughts or things said to oneself, if they do not become engrained and if the person does not continue with them, are forgiven according to the consensus of the ‘ulamā’, because people have no choice in their occurrence and no way of disengaging themselves from it. That is what is meant by [the hadith] which is reliably recorded in the Ṣaḥīḥ, according to which the Messenger of Allah
said: “Allah will pardon my Ummah for what their egos say to them, as long as they do not speak it or act on it.”
The ‘ulamā’ hold that this refers to ideas and passing thoughts. They say that it is the same whether these ideas are backbiting, kufr, or anything else. So whoever has a thought of kufr which is just a notion that he has no intention of acting upon, and he fends it off immediately, is not a disbeliever and there is no sin on him.
We mentioned this earlier, in the chapter on the whisperings of Shayṭān, in the authentic hadith in which [certain of the Companions] said: “Messenger of Allah, some [of us] find [in our minds] things that they consider too appalling to talk about.” He replied: “That is the manifestation of faith.” [3].There are also other things we mentioned there, and things in the same sense.
The reason for pardoning is the one which we have mentioned, namely one’s inability to avoid it. It is only possible to avoid continuing with it, and therefore persisting in it and fixing the heart on it is ḥarām. Whenever these thoughts of backbiting or any other sin arise, it is obligatory to ward them off by turning away from them, and to remember possible interpretations that would change it from its apparent sense.
Imam Abū Ḥāmid al-Ghazālī says in his Iḥyā’ [4].: “When suspicion occurs in your heart, it comes from the whisperings of Shayṭān, which he directs towards you. It is imperative that you reject it, for he is the worst sinner. Allah said: ‘O you who believe, if a sinner comes to you with any news, ascertain the truth, lest you harm people unwittingly, and afterwards become full of remorse for what you have done.’ [5].

“It is not permissible to believe Iblīs, so even if there is evidence to indicate some vice but the contrary of that is conceivable, it is not permissible to think evil. Among the signs of suspicion is that your heart changes towards [the accused person] from what it was before and you avoid him, you find him annoying, your respect and honour for him diminish, and you become concerned with his evil deeds, for Shayṭān sometimes suggests to the heart that people have done evil by the lowest and least imaginings. He puts it in a person’s heart that ‘this [suspicion] arises from your intelligence and astuteness and the acuteness of your vigilance, and that “A believer sees with the light of Allah”.’ In reality he is speaking with the deception and injustice of Shayṭān. Even if a just person corroborates [your suspicion], do not believe him and do not disbelieve him, so that you do not think evil of either of them. Whenever the thought that a Muslim is evil occurs to you, you should have all the more respect and esteem for him, for this angers Shayṭān and chases him away from you and then he will not inculcate similar suspicions in you for fear that you may start making du‘ā’ for [that person]. And if you know about the faults of a Muslim from indisputable evidence, you should give him advice and counsel in secret, and not let Shayṭān deceive you into backbiting him. When you admonish him, do not admonish him while you feel happy to know about his shortcomings, thus causing him to look at you with the eye of honour while you look at him with disdain. Rather, you should aim to free him from sin while you are as sad for him as you would be for yourself if some defect found its way into you. It is essential that it be greatly preferable to you that he abandon that shortcoming without you giving him advice, rather than him abandoning it because of your counsel.” Those are the words of al-Ghazālī.
I say: “We have stated that it is compulsory for a person, when an evil thought or suspicion occurs to him, to stop it, unless there is some religious benefit that calls for reflection on it. If that is called for, however, it is permissible to suspect a person and to investigate him, as in the case of investigating witnesses and narrators of hadiths and others whom we have mentioned in the chapter on what is permissible in backbiting.”
References
[1] Qur’ān 49:12.
[2] Al-Bukhārī (6064) and Muslim (2563).
[3] Muslim (132), with a slight variation in the wording.
[4] Iḥyā ’ ‘ulūm ad-dīn (3/147–148), slightly adapted.
[5] Qur’ān 49:6.