Genesis 17:12 "And every male among you who is eight days old shall be circumcised throughout your generations, a servant who is born in the house or who is bought with money from any foreigner, who is not of your descendants.

Leviticus 12:3 'On the eighth day the flesh of his foreskin shall be circumcised.

Luke 2:21 And when eight days had passed, before His circumcision, His name was then called Jesus, the name given by the angel before He was conceived in the womb.

Philippians 3:5 circumcised the eighth day, of the nation of Israel, of the tribe of Benjamin, a Hebrew of Hebrews; as to the Law, a Pharisee; (NASB ©1995)