Sahih al-Bukhari 1294
Book 23: Funerals (Al-Janaa'iz) · Narrated by `Abdullah
Arabic
حَدَّثَنَا أَبُو نُعَيْمٍ، حَدَّثَنَا سُفْيَانُ، حَدَّثَنَا زُبَيْدٌ الْيَامِيُّ، عَنْ إِبْرَاهِيمَ، عَنْ مَسْرُوقٍ، عَنْ عَبْدِ اللَّهِ ـ رضى الله عنه ـ قَالَ قَالَ النَّبِيُّ صلى الله عليه وسلم " لَيْسَ مِنَّا مَنْ لَطَمَ الْخُدُودَ، وَشَقَّ الْجُيُوبَ، وَدَعَا بِدَعْوَى الْجَاهِلِيَّةِ ".
English translation
Narrated `Abdullah:the Prophet (ﷺ) said, "He who slaps his cheeks, tears his clothes and follows the ways and traditions of the Days of Ignorance is not one of us
Reference: Sahih al-Bukhari 1294, Book of Funerals (Al-Janaa'iz). English translation by Dr. Muhammad Muhsin Khan.