Luke 1:59
and on the eighth day they came to circumcise the child: and they would have called him Zacharias, after the name of his father:
Luke 2:21
And when eight days were fulfilled for the circumcising of the child, his name was called JESUS, having been so called by the angel before He was conceived in the womb.
Philippians 3:5
having been circumcised on the eighth day, of the race of Israel, of the tribe of Benjamin, an Hebrew of Hebrews, with respect to the law a pharisee,
Acts 7:8
And He gave him the covenant of circumcision: and he begat Isaac, and circumcised him on the eighth day; and Isaac Jacob, and Jacob the twelve patriarchs.