Thou shalt fear the LORD thy God, and serve him, and shalt swear by his name.
Shalt swear by his name. The reference is to solemn and judicial oaths, an appeal to God being evidently sanctioned by the terms of the third commandment, though limited in practice to grave occasions, and directed by serious considerations. (Cf. Matthew 5:33-37; James 5:12, which refer to swearing in common conversation.