Deuteronomy 4:14 (ESV)

14 And the LORD commanded me at that time to teach you statutes and rules, that you might do them in the land that you are going over to possess.

After the Lord's revelation at Horeb/Sinai, he commanded Moses to teach Israel the ordinances of the Lord, in order for Israel to do them in the Promised Land. This recollection by Moses occurs at a time where once again he is teaching Israel, this time the post-Sinai generation, the ordinances of the Lord prior to their entry into the land of promise.