Leviticus 15:15

And the priest shall offer them, the one [for] a sin offering, and the other [for] a burnt offering,.... As in the case of a new mother who is poor, and of a poor leper, Leviticus 12:8;

and the priest shall make atonement for him before the Lord for his issue; which, though not in itself sinful, yet might be occasioned by sin, for which the atonement was made: or, however, it was a ceremonial uncleanness, and therefore a ceremonial expiation must he made for it, typical of the atonement by the blood and sacrifice of Christ, by which all kinds of sin is expiated and removed.