Psalms 119:142

Observe, 1. That God's word is righteousness, and it is an everlasting righteousness. It is the rule of God's judgment, and it is consonant to his counsels from eternity and will direct his sentence for eternity. The word of God will judge us, it will judge us in righteousness, and by it our everlasting state will be determined. This should possess us with a very great reverence for the word of God that it is righteousness itself, the standard of righteousness, and it is everlasting in its rewards and punishments. 2. That God's word is a law, and that law is truth. See the double obligation we are under to be governed by the word of God. We are reasonable creatures, and as such we must be ruled by truth, acknowledging the force and power of it. If the principles be true, the practices must be agreeable to them, else we do not act rationally. We are creatures, and therefore subjects, and must be ruled by our Creator; and whatever he commands we are bound to obey as a law. See how these obligations are here twisted, these cords of a man. Here is truth brought to the understanding, there to sit chief, and direct the motions of the whole man; but, lest the authority of that should become weak through the flesh, here is a law to bind the will and bring that into subjection.

— Matthew Henry's Concise Commentary (public domain)