Exodus 22:30
You shall do the same with your oxen and with your sheep: seven days it shall be with its mother; on the eighth day you shall give it to me.
Leviticus 22:27
"When an ox or sheep or goat is born, it shall remain seven days with its mother, and from the eighth day on it shall be acceptable as a food offering to the LORD.
Deuteronomy 15:19
"All the firstborn males that are born of your herd and flock you shall dedicate to the LORD your God. You shall do no work with the firstborn of your herd, nor shear the firstborn of your flock.
Exodus 13:12
you shall set apart to the LORD all that first opens the womb. All the firstborn of your animals that are males shall be the LORD's.
Leviticus 12:3
And on the eighth day the flesh of his foreskin shall be circumcised.