C. F. Keil and Franz Delitzsch on Deuteronomy 6:1

On loving Jehovah, the one God, with all the Heart.

Announcement of the commandments which follow, with a statement of the reason for communicating them, and the beneficent results of their observance. המּצוה, that which is commanded, i.e., the substance of all that Jehovah had commanded, synonymous therefore with the Thorah (Deu 4:44). The words, “the statutes and the rights,” are explanatory of and in apposition to “the commandment.” These commandments Moses was to teach the Israelites to keep in the land which they were preparing to possess (cf. Deu 4:1).