Sahih Muslim
Sahih Muslim 2119 b
The Permissibility Of Branding Animals Anywhere But On The Face, And This Is Recommended In The Case Of Animals Given As Zakat Ot Jizyah
Arabic hadith text
حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، حَدَّثَنَا شُعْبَةُ، عَنْ هِشَامِ بْنِ زَيْدٍ،
قَالَ سَمِعْتُ أَنَسًا، يُحَدِّثُ أَنَّ أُمَّهُ، حِينَ وَلَدَتِ انْطَلَقُوا بِالصَّبِيِّ إِلَى النَّبِيِّ صلى الله عليه وسلم
يُحَنِّكُهُ قَالَ فَإِذَا النَّبِيُّ صلى الله عليه وسلم فِي مِرْبَدٍيَسِمُ غَنَمًا .قَالَ شُعْبَةُ وَأَكْثَرُ عِلْمِي
أَنَّهُ قَالَ فِي آذَانِهَا
Translation
Anas reported that when his mother gave birth to a child they brought that child to Allah's Messenger (ﷺ) so that he might chew some dates and touch his palate with them. and Allah's Apostle (ﷺ) was at that time in the fold busy in cauterising the animals Shu'ba said
So far as I know (he was cauterising) their ears.