Concerning the offering of a newborn bull, sheep, or goat, the Lord told Israel,

“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” (Leviticus 22.27).

This may have been for the benefit of the animal mother, but whatever the reason, the Lord wanted that seven day period, even as He required seven days for several other things.