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 has lost most of its horn or ear. Qatadah said: I mentioned that to Sa’eed bin al-Musayyab and he said. [That refers to] one that has lost half or more (of its horn or ear).