2 And that man was not justified by these things, but that they were given as a sign to the people, this fact shows—that Abraham himself, without circumcision and without observance of Sabbaths, “believed God, and it was imputed unto him for righteousness; and he was called the friend of God.” Then, again, Lot, without circumcision, was brought out from Sodom, receiving salvation from God. So also did Noah, pleasing God, although he was uncircumcised, receive the dimensions [of the ark], of the world of the second race [of men].
Enoch, too, pleasing God, without circumcision, discharged the office of God's legate to the angels although he was a man, and was translated, and is preserved until now as a witness of the just judgment of God, because the angels when they had transgressed fell to the earth for judgment, but the man who pleased [God] was translated for salvation. Moreover, all the rest of the multitude of those righteous men who lived before Abraham, and of those patriarchs who preceded Moses, were justified independently of the things above mentioned, and without the law of Moses. As also Moses himself says to the people in Deuteronomy: “The Lord your God formed a covenant in Horeb. The Lord formed not this covenant with your fathers, but for you.”
Source: Adversus haereses (New Advent)