Jamieson, Fausset and Brown on 1 Kings 2:3

3. keep the charge of the Lord thy God--that is, the divine law in all its ceremonial as well as moral requirements. But particular reference was intended to its political institutions, as it was only by strictly maintaining the conduct that became the Hebrew monarch (De 17:10-20), that he would secure the blessing of peace and prosperity to his reign (see on De 4:5; De 29:10).