David’s conscience here witnesses for him,

I. That his practices were good. 1. He loved God’s testimonies, he loved them exceedingly. Our love to the word of God must be a superlative love (we must love it better than the wealth and pleasure of this world), and it must be a victorious love, such as will subdue and mortify our lusts and extirpate carnal affections. 2. He kept them, his soul kept them. Bodily exercise profits little in religion; we must make heart-work of it or we make nothing of it. The soul must be sanctified and renewed, and delivered into the mould of the word; the soul must be employed in glorifying God, for he will be worshipped in the spirit. We must keep both the precepts and the testimonies, the commands of God by our obedience to them and his promises by our reliance on them.

II. That he was governed herein by a good principle: “Therefore I have kept thy precepts, because by faith I have seen thy eye always upon me; all my ways are before thee; thou knowest every step I take and strictly observest all I say and do. Thou dost see and accept all that I say and do well; thou dost see and art displeased with all I say and do amiss.” Note, The consideration of this, that God’s eye is upon us at all times, should make us very careful in every thing to keep his commandments, Gen. 17:1.