Maliks Muwatta Book 20, Hadith Number 145.

Section : What are Acceptable as Sacrificial Animals (Hadys).

ahya related to me from Malik from Hisham ibn Urwa that his father said, “If necessary, ride on your sacrificial animal, without burdening it, and if necessary, drink its milk after its young one has drunk its fill, and when you sacrifice it, sacrifice the young one with it.”