John Calvin Commentary Psalms 119:118

"Thou hast set at nought all them that err from thy statutes; For their deceit is falsehood." — Psalms 119:118 (ASV)

You have trodden under foot all those who wander from your statutes. By treading under foot, he means that God overthrows all the despisers of his law and casts them down from that loftiness they assume for themselves. The phrase is directed against the foolish, or rather frantic, confidence with which the wicked are inflated when they recklessly deride the judgments of God; and, what is more, do not hesitate to magnify themselves against him, as if they were not subject to his power.

The last clause should be particularly noticed: for their deceit is falsehood. By these words, the prophet teaches that the wicked gain nothing by their wiles, but that they are rather entangled in them, or eventually discover that they were mere sleight of hand. Those ignorantly mar the sense who interpose the copula and, as if it had been said that deceit and falsehood were in them. The word רמוה, remyah, signifies a subtle and crafty device. Interpreters, indeed, often translate it thought; but this term does not sufficiently express the propriety and force of the Hebrew word.

The prophet means that, however well pleased the wicked are with their own cunning, they yet do nothing else than deceive themselves with falsehood. And it was necessary to add this clause; for we see how the great bulk of mankind are fatally intoxicated with their own vain imaginations, and how difficult it is to believe what is here asserted—that the more shrewd they are in their own estimation, the more do they deceive themselves.