C.H. Spurgeons's The Treasury of David
Verse 19. But verily God hath heard me. Sure sign this that the petitioner was no secret lover of sin. The answer to his prayer was a fresh assurance that his heart was sincere before the Lord. See how sure the psalmist is that he has been heard; it is with him no hope, surmise, or fancy, but he seals it with a verily. Facts are blessed things when they reveal both God's heart as loving, and our own heart as sincere.
He hath attended to the voice of my prayer. He gave his mind to consider my cries, interpreted them, accepted them, and replied to them; and therein proved his grace and also my uprightness of heart. Love of sin is a plague spot, a condemning mark, a killing sign, but those prayers, which evidently live and prevail with God, most clearly arise from a heart which is free from dalliance with evil. Let the reader see to it, that his inmost soul be rid of all alliance with iniquity, all toleration of secret lust, or hidden wrong.
EXPLANATORY NOTES AND QUAINT SAYINGS
Verse 18-20. See Psalms on "Psalms 66:18" for further information.
HINTS FOR PASTORS AND LAYPERSONS
The test admitted.
The test applied.
The test approved.
Verse 19. The fact that God has heard prayer.