Your righteousness is an everlasting righteousness, and your law is the truth.
Read Chapter 119
Augustine of Hippo
140. It is no wonder that they have forgotten the words of God, who have chosen to set up their own righteousness, ignorant of the righteousness of God; but he, the younger, hath not forgotten, for he hath not wished to have a righteousness of his own, but that of God, of which he now also saith, "Thy righteousness is an everlasting righteousness, and Thy law is the truth" (ver. 142). For how is not the law truth, through which came the knowledge of sin, and that which giveth testimony of the righteousness of God? For thus the Apostle saith: "The righteousness of God is manifested, being witnessed by the Law and the Prophets."