Thy word have I hid in mine heart - Compare the notes at Psalms 37:31. The word rendered “hid” means properly to conceal, so that a thing may be secret, private, inaccessible; then, to lay up in private, to treasure up. to hoard - as money or jewels - commonly “hidden” from public view. Job 20:26; Psalms 17:14. Then it means to lay up in one’s heart, as a secret, inaccessible place; to hide one’s thoughts; purposes, designs; or to lay up knowledge or wisdom in the heart as a treasure, Job 10:13; Proverbs 2:1; Proverbs 7:1. The meaning here is, that he had “treasured” up the word of God, as the most valuable thing, in his heart; it was “there,” though unseen; it constituted the secret power by which he was governed; it was permanently deposited there, as the most valuable of his treasures.
That I might not sin against thee - That it might protect me from sinning against thee. That I might be continually guided by its precepts; that I might be admonished of duty; that I might be deterred from going astray.