Leviticus 22:26-30

And the LORD spoke to Moses, saying: “When a bull or a sheep or a goat is born, it shall be seven days with its mother; and from the eighth day and thereafter it shall be accepted as an offering made by fire to the LORD. Whether it is a cow or ewe, do not kill both her and her young on the same day. And when you offer a sacrifice of thanksgiving to the LORD, offer it of your own free will. On the same day it shall be eaten; you shall leave none of it until morning: I am the LORD.