Exodus 22:30
Do the same with your oxen and with your sheep. Its mother may keep it for seven days. On the eighth day give it to me.
Leviticus 22:27
He said: When a calf, a lamb, or a goat is born, it must stay with its mother for seven days. It may be accepted as a sacrifice by fire to Jehovah from the eighth day on.
Deuteronomy 15:19
To Jehovah your God you shall consecrate all the firstborn males that are born of your herd and of your flock; you shall not work with the firstborn of your herd, nor shear the firstborn of your flock.
Exodus 13:12
sacrifice every firstborn male offspring to Jehovah. The firstborn male offspring of each of your animals belongs to Jehovah.
Leviticus 12:3
The boy must be circumcised when he is eight days old.