Sahih Muslim 2612
Sahih Muslim · Book 45: The Book of Virtue, Enjoining Good Manners, and Joining of the Ties of Kinship · The Prohibition Of Striking The Face
Abu Huraira reported Allah's Messenger (ﷺ) as saying:
حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى ، حَدَّثَنِي عَبْدُ الصَّمَدِ ، حَدَّثَنَا هَمَّامٌ ، حَدَّثَنَا قَتَادَةُ ، عَنْ يَحْيَى، بْنِ مَالِكٍ الْمَرَاغِيِّ - وَهُوَ أَبُو أَيُّوبَ - عَنْ أَبِي هُرَيْرَةَ ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " إِذَا قَاتَلَ أَحَدُكُمْ أَخَاهُ فَلْيَجْتَنِبِ الْوَجْهَ " .
When any one of you fights with his brother, he should avoid the face.