By Allah, I do not cauterise (the animal) but on a part at a distance from the face, and commanded (for the cauterisation) of his ass and it was cauterised on the buttocks and he was the first to cauterise on the buttocks. (Using translation from Muslim 2118)
أَنَّ نَاعِمًا أَبَا عَبْدِ اللهِ مَوْلَى أُمِّ سَلَمَةَ زَوْجِ النَّبِيِّ ﷺ حَدَّثَهُ أَنَّهُ سَمِعَ ابْنَ عَبَّاسٍ ؓ يَقُولُ رَأَى رَسُولُ اللهِ ﷺ حِمَارًا مُوسَمَ الْوَجْهِ فَأَنْكَرَ ذَلِكَ قَالَ فَوَاللهِ لَا أَسِمُهَا إِلَى أَقْصَى شَيْءٍ مِنَ الْوَجْهِ فَأَمَرَ بِحِمَارِهِ فَكُوِيَ فِي جَاعِرَتَيْهِ فَهُوَ أَوَّلُ مَنْ كَوَى فِي الْجَاعِرَتَيْنِ