Chapter 19: The Book on Sacrifices
Narrated 'Uqbah bin 'Amir: That the Messenger of Allah (ﷺ) gave him sheep to distribute among his Companions as a sacrifice. "There remained a young male kid or a young billy goat, so I mentioned that to the Messenger of Allah (ﷺ) and he said: 'Sacrifice it for yourself.'"
Waki' said: "The Jadha' among sheep is seven or six months."
Jami at-Tirmidhi 1500