Daily Hadith Sat 09-Sep-2017 - 17 Dhul-Hijjah 1438 حديث اليوم
باب تحريم قوله لمسلم : يا كافر
عَنِ ابنِ عُمَرَ رَضِيَ اللَّه عَنْهُمَا قَالَ : قَالَ رَسُولُ اللَّه صَلّى اللهُ عَلَيْهِ وسَلَّم : « إِذا قَالَ الرَّجُـلُ لأَخِيهِ : يَا كَافِر ، فَقَدْ بَاءَ بِهَا أَحَدُهُما ، فَإِنْ كَان كَمَا قَالَ وَإِلاَّ رَجَعَتْ عَلَيْهِ » متفقٌ عليه .
1732/326 - رياض الصالحين
Prohibition of Calling a Muslim an Infidel
Ibn `Umar (May Allah be pleased with them) said: The Messenger of Allah (PBUH) 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].


Commentary:
We learn from this Hadith that to call a Muslim a Kafir is strictly prohibited because if the one who has been called as such does not have the traits which makes him a Kafir, then the one who says it will be held Kafir.

326/1732 - Riyad Us-Saliheen (Gardens of the Righteous)
Sat 09-Sep-2017 - 17 Dhul-Hijjah 1438