Moses speaks this of himself in the third person, which is very usual in the Hebrew language. The law is called their inheritance, partly because the obligation of it was hereditary, passing from parents to their children, and partly because this was the best part of all their inheritance and possessions, the greatest of all those gifts and favours which God bestowed upon them.
Related Commentaries of Deuteronomy 33:4
Deuteronomy 33:4
4 Moses commanded us a law, even the inheritance of the congregation of Jacob.