Leviticus 12:3

And in the eighth day the flesh of his foreskin shall be
circumcised.
] Or the foreskin of his flesh, that is, of the man child born according to the law, ( Genesis 17:12 ) and this seems to furnish out a reason why a male child was not circumcised before the eighth day, and why it was then, because before that its mother was in her separation and uncleanness, and then was freed from it; and so the Targum of Jonathan. The circumcision of a male child on the eighth day was religiously observed, and even was not omitted on account of the sabbath, when the eighth day happened to be on that, (See Gill on John 7:22) (See Gill on John 7:23). It is an observation of Aben Ezra on this place, that the wise men say "in the day", and not in the night, lo, he that is born half an hour before the setting of the sun is circumcised after six days and a half, for the day of the law is not from time to time.