And when Abram was ninety-nine years old, the Lord appeared to
Abram, and said to him, I am the Almighty God; walk before me, and be thou
perfect... my covenant is with thee, and thou shalt be a father of many
nations. Neither shall thy name any more be called Abram, but thy name
shall be Abraham; for a father of many nations have I made thee... and I
will establish my covenant between me and thee and thy seed after thee in
their generations for an everlasting covenant, to be a God unto thee, and
to thy seed after thee. And I will give unto thee, and to thy seed after
thee, the land wherein thou art a stranger, all the land of Canaan, for an
everlasting possession; and I will be their God... This is my covenant,
which you shall keep, between me and you and thy seed after thee; Every
man child among you shall be circumcised... he that is eight days old
shall be circumcised among you, every man child in your generations, he
that is born in the house, or bought with money of any stranger, which is
not of thy seed. He that is born in in thy house, and he that is bought
with thy money, must needs be circumcised: and my covenant shall be in
your flesh for an everlasting covenant. And the uncircumcised man child
whose flesh of his foreskin is not circumcised, that soul shall be cut off
from his people; he hath broken my covenant.
Gen. 17:1-14