Albert Barnes Commentary Leviticus 19:3

"Ye shall fear every man his mother, and his father; and ye shall keep my sabbaths: I am Jehovah your God." — Leviticus 19:3 (ASV)

Compare Exodus 20:8, Exodus 20:12, and Exodus 31:13-14. The two laws repeated here are the only laws in the Decalogue that assume a positive shape, all the others being introduced by the formula, Thou shalt not. These express two great central points, the first belonging to natural law and the second to positive law, in the maintenance of the well-being of the social body of which Yahweh was the acknowledged king.