Abu Huraira reported God’s Messenger as saying, “Does he who raises his head before the <i>imam</i> not fear that God may change his head into a donkey’s?” (Bukhari and Muslim.)

وَعَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «أَمَا يَخْشَى الَّذِي يَرْفَعُ رَأْسَهُ قَبْلَ الْإِمَامِ أَنْ يُحَوِّلَ اللَّهُ رَأْسَهُ رَأْسَ حمَار»