Keil & Delitzsch

Recognising the infamy of such black ingratitude, he prays for instruction as to the ways which he must take according to the precepts of God (Psa 18:22). The will of God, it is true, lies before us in God's written word, but the expounder required for the right understanding of that word is God Himself. He prays Him for knowledge; but in order to make what he knows a perfect and living reality, he still further needs the grace of God, viz., both His enlightening and also His guiding grace.