You shall not take the name of the LORD your God in vain, for the LORD will not leave anyone unpunished who takes His name in vain.
Exodus 20:7. Thou shalt not take the name. There is a manifest synecdoche in this Commandment; for in order that God may procure for His name its due reverence, He forbids its being taken in vain, especially in oaths. Whence we infer on the other hand an affirmative commandment, that every oath should be a testimony of true piety, whereby the majesty of God Himself should obtain its proper glory.
God spoke these words Himself with dreadful pomp, not merely whispered through conscience or providence, but with the authority of Jehovah, the self-existent One. He bound Israel threefold: by His nature as eternal Lord, by covenant as their God, and by His power to reward obedience and punish disobedience.
AI summary
Commenting on Exodus 20:1-11
Thou shall not take the name of the Lord God in vain,.... Make use of the name Lord or God, or any other name and epithet of the divine Being, in a light and trifling way, without any show of reverence of him, and affection to him; whereas the name of God ought never to be mentioned but in a grave and serious manner, and...