Leviticus 15:28-31

28But if she be cleansed of her issue, then she shall number to herself seven days, and after that she shall be clean. 29And on the eighth day she shall take unto her two turtle-doves, or two young pigeons, and bring them unto the priest, to the door of the tent of meeting. 30And the priest shall offer the one for a sin-offering, and the other for a burnt-offering; and the priest shall make atonement for her before Jehovah for the issue of her uncleanness.

31Thus shall ye separate the children of Israel from their uncleanness, that they die not in their uncleanness, when they defile my tabernacle that is in the midst of them.