David, having in the foregoing verse reflected upon his covenants with God, here reflects upon his prayers to God, and renews his petition. Observe, 1. What he prayed for. Having taken God for his portion, he entreated his favour, as one that knew he had forfeited it, was unworthy of it, and yet undone without it, but for ever happy if he could obtain it. We cannot demand God's favour as a debt, but must be humble suppliants for it, that God will not only be reconciled to us, but accept us and smile upon us. He prays, "Be merciful to me, in the forgiveness of what I have done amiss, and in giving me grace to do better for the future." 2. How he prayed - with his whole heart, as one that knew how to value the blessing he prayed for. The gracious soul is entirely set upon the favour of God, and is therefore importunate for it. I will not let thee go except thou bless me. 3. What he pleaded - the promise of God: "Be merciful to me, according to thy word. I desire the mercy promised, and depend upon the promise for it." Those that are governed by the precepts of the word and are resolved to keep them (Psa 119:57) may plead the promises of the word and take the comfort of them.