To the conductor, a Psalm of David, which was given to him by the prophet Nathan. This is what the scripture says (Proverbs 18:21): "Death and life are in the power of the tongue." A person's tongue leads him to the afterlife. What caused David to enter the World to Come?
It was his mouth, which said "I have sinned," as it is written (2 Samuel 12:13): "And David said to Nathan, 'I have sinned.'" He was in darkness, but God illuminated him, as it is written (Psalm 18:29): "For You will light my candle; the Lord my God will enlighten my darkness." And it is said (Isaiah 58:10): "And your darkness shall be like noonday." David said before God, "I ask of You to look at the beauty of Israel."
And so God said to Solomon (1 Kings 3:14), "And if you will walk in My ways, as your father David walked." David said, "Master of the Universe, do not look at the time I sinned before You." And it is said (Psalm 51:11), "Hide Your face from my sins." Once Nathan the prophet said to him (2 Samuel 12:13), "The Lord has also put away your sin." Therefore, this Psalm was composed: "To the conductor, a Psalm of David, which was given to him by the prophet Nathan."