Musnad Ahmad 5:741

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Salamah ibn Kuhayl, who said: I heard Hujayyah ibn 'Adi, who said: I heard 'Ali ibn Abi Talib, and a man asked him about the cow, and he said: "For seven." And he asked him about the lame [animal], and he said: "When it reaches the place of sacrifice." And he was asked about the horn [that is broken], and he said: "It does not harm it." And 'Ali said: "The Messenger of Allah, may Allah bless him and grant him peace, commanded us to examine the eye and the ear."