Psalm 66:18 Meaning

16Come and hear, all ye that fear God, and I will declare what he hath done for my soul.

17I cried unto him with my mouth, and he was extolled with my tongue.

18If I regard iniquity in my heart, the Lord will not hear me:

19But verily God hath heard me; he hath attended to the voice of my prayer.

20Blessed be God, which hath not turned away my prayer, nor his mercy from me.