Musnad Ahmad 1066
It was narrated that Qatadah said:
I heard Jurayy bin Kulaib narrate that ‘Ali (رضي الله عنه) said: The Messenger of Allah (ﷺ) forbade [for sacrifice] any animal that was missing most of its ear or horn. I asked Sa`eed bin al-Musayyab: What does missing most of its ear or horn mean? He said: When half or more [of an animal`s ear or horn] is missing.
حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ مَهْدِيٍّ، حَدَّثَنَا شُعْبَةُ، عَنْ قَتَادَةَ، قَالَ سَمِعْتُ جُرَيَّ بْنَ كُلَيْبٍ، يُحَدِّثُ عَنْ عَلِيٍّ، رَضِيَ اللَّهُ عَنْهُ قَالَ نَهَى رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ عَنْ عَضَبِ الْأُذُنِ وَالْقَرْنِ قَالَ فَسَأَلْتُ سَعِيدَ بْنَ الْمُسَيَّبِ مَا الْعَضَبُ فَقَالَ النِّصْفُ فَمَا فَوْقَ ذَلِكَ‏.‏