Musnad Ahmad 5:172

Waki’ narrated to us, Sufyan narrated to us, from Salamah ibn Kuhayl, from Hujayyah, who said: A man asked Ali about the cow [for sacrifice], and he said: "It is for seven." He said: "What about one with a broken horn?" He replied: "It does not harm you." He said: "What about the lame one?" He replied: "When you reach the place of sacrifice, then slaughter it. The Messenger of Allah (ﷺ) commanded us to carefully inspect the eye and the ear."