At the close of the second period of purification, a correct sacrifice had to be made. The Lord required both a lamb for a burnt offering as well as a bird for a sin offering. Through these two sacrifices the Israelite mother was being readmitted to the religious life of Israel.
6 “And when the days of her purifying are completed, whether for a son or for a daughter, she shall bring to the priest at the entrance of the tent of meeting a lamb a year old for a burnt offering, and a pigeon or a turtledove for a sin offering,