Halakhah zu Dewarim 27:9

The doctrine of matrilineal succession and the exclusion of the principle of patrilineal identity as a sufficient criterion of Jewish identity is Sinaitic in origin. Whether or not, historically, a different principle pertained prior to the Sinaitic covenant is entirely irrelevant. Insofar as the community of Israel is concerned, innumerable provisions of the Noachide Code which were binding upon all people prior to Sinai were supplanted by the Sinaitic covenant. With regard to the giving of the Torah at Mount Sinai, Scripture declares, "This day thou art become a people unto the Lord thy God" (Deuteronomy 27:9). Prior to Sinai there existed no community of Israel. Even as the concept of the peoplehood of Israel and the sanctity of Israel date from Sinai, so also are the criteria of membership in the community of Israel prescribed by the covenant entered into at Sinai.