TSK · Genesis 21:4

This is my covenant, which ye shall keep, between me and you and thy seed after thee: every male among you shall be circumcised.

And when a stranger shall sojourn with thee, and will keep the passover to Jehovah, let all his males be circumcised, and then let him come near and keep it; and he shall be as one that is born in the land: but no uncircumcised person shall eat thereof.

What thing soever I command you, that shall ye observe to do: thou shalt not add thereto, nor diminish from it.

And it came to pass on the eighth day, that they came to circumcise the child; and they would have called him Zacharias, after the name of the father.

Moses hath given you circumcision (not that it is of Moses, but of the fathers); and on the sabbath ye circumcise a man.