Exodus 13:11-13

11And it shall be when Jehovah hath brought thee into the land of the Canaanites, as he hath sworn to thee and to thy fathers, and hath given it thee,

12that thou shalt offer unto Jehovah all that breaketh open the womb, and every firstling that cometh of cattle which is thine: the males [shall be] Jehovah's.

13And every firstling of an ass shalt thou ransom with a lamb; and if thou do not ransom it, thou shalt break its neck; and every firstborn of a man among thy sons shalt thou ransom.