Leviticus 12:5 - Joseph Benson’s Commentary on the Old and New Testaments

Threescore and six days The time in both particulars is double to the former; the law, as some think, being adapted to a received opinion that women are sooner purified after the birth of males than of females; an opinion which, however questioned, Grotius shows to be supported by no less authority than that of Aristotle and Hippocrates. Others, however, suppose that this difference was made to put an honour on the ordinance of circumcision, which, being administered to the males, put an end to that pollution sooner than otherwise would have been the case.