(53) باب إِثْمِ مَنْ رَفَعَ رَأْسَهُ قَبْلَ الإِمَامِ
Narrated Abu Huraira:
The Prophet (ﷺ) said, "Isn't he who raises his head before the Imam afraid that Allah may transform his head into that of a donkey or his figure (face) into that of a donkey?"
Reference: Sahih al-Bukhari 691
In-book reference: Book 10, Hadith 86
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 1, Book 11, Hadith 660