The sin of the one who raises his head before the Imam (raises his head)

Sahih al-Bukhari · Book 10 · Hadith 691

حَدَّثَنَا حَجَّاجُ بْنُ مِنْهَالٍ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ مُحَمَّدِ بْنِ زِيَادٍ، سَمِعْتُ أَبَا هُرَيْرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏"‏ أَمَا يَخْشَى أَحَدُكُمْ ـ أَوْ لاَ يَخْشَى أَحَدُكُمْ ـ إِذَا رَفَعَ رَأْسَهُ قَبْلَ الإِمَامِ أَنْ يَجْعَلَ اللَّهُ رَأْسَهُ رَأْسَ حِمَارٍ أَوْ يَجْعَلَ اللَّهُ صُورَتَهُ صُورَةَ حِمَارٍ ‏"‏‏.‏

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?"