Sunan Ibn Majah, Book 5, Hadith 1014 (In-Book) ⓘ
It was narrated that Abu Hurairah said: “The Messenger of Allah said: ‘Does not the one who raises his head before the Imam fear that Allah may turn his head into the head of a donkey?’”
حَدَّثَنَا حُمَيْدُ بْنُ مَسْعَدَةَ، وَسُوَيْدُ بْنُ سَعِيدٍ، قَالاَ حَدَّثَنَا حَمَّادُ بْنُ زَيْدٍ، حَدَّثَنَا مُحَمَّدُ بْنُ زِيَادٍ، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ " أَلاَ يَخْشَى الَّذِي يَرْفَعُ رَأْسَهُ قَبْلَ الإِمَامِ أَنْ يُحَوِّلَ اللَّهُ رَأْسَهُ رَأْسَ حِمَارٍ " .
also referenced under: Hadith 961 (Reference) & Volume 2, Book 5, Hadith 961 (DarusSalam)