Luke 2:22

And when the days of their purification according to the law of Moses were fulfilled, they brought him up to Jerusalem, to present him to the Lord (as if is written in the law of the Lord, Every male that openeth the womb shall be called holy to the Lord).

Their purification ... carries some hint that Jesus needed purification also; and, if so, this has reference to ceremonial uncleanness, a thing Jesus suffered as an inherent factor of the incarnation. He was "made to be sin" on our behalf (2 Corinthians 5:21). Again from Childers:

His whole life shows that he identified himself with this sinful race - though he was sinless. Jesus always submitted to religious rites which were necessary for sinful men, even though they were not really necessary for him.[23]

For Old Testament teachings regarding the purification of women after childbirth, and the redemption of the firstborn, see: Leviticus chapter 12; Exodus 13:2; Numbers 8:16; 18:15. These ceremonies are mentioned here for the sake of showing that all legal requirements under the law were carefully observed.