Charles Ellicott Commentary Leviticus 12:3

"And in the eighth day the flesh of his foreskin shall be circumcised." — Leviticus 12:3 (ASV)

And in the eighth day. —When the seven days had passed during which the mother remained unclean, the boy is to be circumcised, since on the eighth day the first period of her extreme state of impurity ceases, and she no longer imparts defilement to whoever or whatever she touches. For the rite of circumcision, see Genesis 17:10; Genesis 17:13.