ENOfficial
It was narrated from Jurayy bin Kulaib that he heard `Ali (رضي الله عنه) say: The Messenger of Allah (ﷺ) forbade sacrificing an animal that had lost most of its horn or ear, Qatadah said: I mentioned that to Sa`eed bin Al-Musayyab and he said: Yes, the one that has lost half or more of that.
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، حَدَّثَنَا سَعِيدٌ، عَنْ قَتَادَةَ، عَنْ جُرَيِّ بْنِ كُلَيْبٍ، أَنَّهُ سَمِعَ عَلِيًّا، رَضِيَ اللَّهُ عَنْهُ يَقُولُ نَهَى رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَنْ يُضَحَّى بِأَعْضَبِ الْقَرْنِ وَالْأُذُنِ قَالَ قَتَادَةُ فَذَكَرْتُ ذَلِكَ لِسَعِيدِ بْنِ الْمُسَيَّبِ فَقَالَ نَعَمْ الْعَضَبُ النِّصْفُ أَوْ أَكْثَرُ مِنْ ذَلِكَ.
sunnah.com