Thy word have I hid in mine heart,.... Not only heard and read it, but received it into his affections; mixed it with faith, laid it up in his mind and memory for future use; preserved it in his heart as a choice treasure, where it might dwell richly, and be of service to him on many occasions; and particularly be of the following use: that I might not sin against thee; the word of God is a most powerful antidote against sin, when it has a place in the heart; not only the precepts of it forbid sin, but the promises of it influence and engage to purity of heart and life, and to the perfecting of holiness in the fear of the Lord; and all the doctrines of grace in it effectually teach the saints to deny all sin and worldly lusts, and to live a holy life and conversation; see Co2 7:1.