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.

Let thine hand help me,.... Let thine hand of power help me against mine enemies, and deliver me from them; and let thine hand of providence and grace communicate to me, and supply me with and help me to everything needful for me, for body and soul; for time and eternity, all grace here, and glory hereafter; let thy right hand help me on in my way, hold and uphold me, keep and preserve me safe to heaven and happiness;

for I have chosen thy precepts; not only the good part, which shall not be taken away, and the way of truth, Psa 119:30; but even the commandments of God, which he preferred to the commandments of men, and choose rather to obey the one than the other; having a most ardent affection for them, an high esteem of them, and a strong attachment to them; see Psa 119:127.