[Now] Moses gave you [the ordinance of] circumcision and you circumcise a man on the Sabbath day. (Although it was [first] required by [your] forefathers and not Moses).
And God gave Abraham the Agreement which required circumcision [as an identifying mark] so when Abraham fathered Isaac he circumcised him when he was eight days old. Then Isaac had a son, Jacob; and Jacob had [as sons] the twelve patriarchs [i.e., ruling fathers of families].
Here is what I am saying: The Agreement originally made by God [with Abraham], with its attending promises, was not canceled when the Law of Moses was given some four hundred and thirty years later.