The present essay focuses on Abraham as a symbol or embodiment of the natural law. The starting point is a verse from Genesis, 26:5, which puzzled exegetes from the ancient times as it says that Abraham obeyed God keeping his commands, in a period of human history when the Torah had not yet been given at Sinai. The book examines the relation between natural and revealed law and which role this relation plays in Judaism, starting from Philo De Abrahamo. Then tries to investigate if his exegesis can dialogue with the rabbinic tradition and the author to whom we probably owe the first full doctrine of natural law in the Jewish culture, that is Baruch Spinoza.