Riyad as-Salihin · Chapter 326

Prohibition of Calling a Muslim an Infidel

باب تحريم قوله لمسلم‏:‏ يا كافر

Here an-Nawawi warns against the heavy tongue that throws the word kufr, disbelief, at a fellow Muslim. To declare someone outside the faith is among the gravest accusations a person can make, and these two hadith show that the charge does not vanish into the air. It lands somewhere.

The thread to notice is the principle of return, takfir wrongly aimed comes back upon the one who launched it. This is a powerful restraint on anger and arrogance in disputes, and a reminder that judging hearts and faith belongs to Allah, while details of who is and is not within Islam are matters for qualified scholars, not for heated argument.

Hadith 1732

Ibn 'Umar (May Allah be pleased with them) said:

عن ابن عمر رضي الله عنهما قال‏:‏ قال رسول الله صلى الله عليه وسلم ‏:‏ ‏ "‏إذا قال رجل لأخيه‏:‏ يا كافر، فقد باء بها أحدهما، فإن كان كما قال وإلا رجعت عليه‏" ‏ ‏(‏‏(‏متفق عليه‏)‏‏)‏‏.‏

The Messenger of Allah (ﷺ) said, "When a person calls his brother (in Islam) a disbeliever, one of them will certainly deserve the title. If the addressee is so as he has asserted, the disbelief of the man is confirmed, but if it is untrue, then it will revert to him." [Al-Bukhari and Muslim].

In plain words

Calling a fellow Muslim a disbeliever is so serious that the charge lands on one of the two: if untrue, it returns to the accuser. A strong restraint on rash judgement of others' faith.

Reference : Riyad as-Salihin 1732 In-book reference : Book 17, Hadith 222

Hadith 1733

Abu Dharr (May Allah be pleased with him) said:

وعن أبي ذر رضي الله عنه أنه سمع رسول الله صلى الله عليه وسلم يقول‏:‏ ‏ "‏من دعا رجلا بالكفر، أو قال‏:‏ عدو الله، وليس كذلك إلا حار عليه‏" ‏ ‏(‏‏(‏متفق عليه‏)‏‏)‏‏.‏ حار‏ ‏ رجع‏‏.‏

I heard the Messenger of Allah (ﷺ) saying, "If somebody accuses another of disbelief or calls him the enemy of Allah, such an accusation will revert to him (the accuser) if the accused is innocent." [Al-Bukhari and Muslim].

In plain words

Accusing someone of disbelief or calling him an enemy of Allah rebounds on the accuser if the accused is innocent. Judging hearts belongs to Allah, not to angry speech.

Reference : Riyad as-Salihin 1733 In-book reference : Book 17, Hadith 223