For I have kept the ways of the LORD, and have not wickedly departed from my God.

Matthew Henry's Concise Commentary

18:20-28 Those that forsake the ways of the Lord, depart from their God. But though conscious to ourselves of many a false step, let there not be a wicked departure from our God. David kept his eye upon the rule of God's commands. Constant care to keep from that sin, whatever it be, which most easily besets us, proves that we are upright before God. Those who show mercy to others, even they need mercy. Those who are faithful to God, shall find him all that to them which he has promised to be. The words of the Lord are pure words, very sure to be depended on, and very sweet to be delighted in. Those who resist God, and walk contrary to him, shall find that he will walk contrary to them, Le 26:21-24. The gracious recompence of which David spoke, may generally be expected by those who act from right motives. Hence he speaks comfort to the humble, and terror to the proud; Thou wilt bring down high looks. And he speaks encouragement to himself; Thou wilt light my candle: thou wilt revive and comfort my sorrowful spirit; thou wilt guide my way, that I may avoid the snares laid for me. Thou wilt light my candle to work by, and give me an opportunity of serving thee. Let those that walk in darkness, and labour under discouragements, take courage; God himself will be a Light to them.