Leviticus 12:3

“And every male among you who is eight days old shall be circumcised throughout your generations, one who is born in the house or one who is bought with money from any foreigner, who is not of your seed.

“And you shall do the same with your oxen and with your sheep. It shall be with its mother seven days; on the eighth day you shall give it to Me.

Then David sent messengers and took her, and she came to him, and he lay with her; and when she had purified herself from her uncleanness, she returned to her house.

And it happened that on the eighth day they came to circumcise the child, and they were going to call him Zechariah, after the name of his father.

And when eight days were fulfilled so that they could circumcise Him, His name was called Jesus, the name given by the angel before He was conceived in the womb.

“For this reason Moses has given you circumcision (not because it is from Moses, but from the fathers), and on the Sabbath you circumcise a man.

Some men came down from Judea and began teaching the brothers, “Unless you are circumcised according to the custom of Moses, you cannot be saved.”