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 ) ( 14:22 ) ; 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.