1 Saul was thirty years old when he became king, and he reigned over Israel forty-two years.
1 Samuel 13:1 Cross References - WEB
Exodus 12:5
5 Your lamb shall be without defect, a male a year old. You shall take it from the sheep, or from the goats.
Micah 6:6
6 How shall I come before Yahweh, and bow myself before the exalted God? Shall I come before him with burnt offerings, with calves a year old?