From our Synod's Website and Treasury of Daily Prayer:
David, the greatest of Israel's kings, ruled from about 1010 to 970 B.C. The events of his life are found in 1 Samuel 16 through 1 Kings 2 and in 1 Chronicles 10—29. David was also gifted musically. He was skilled in playing the lyre and the author of no less than 73 psalms, including the beloved Psalm 23. His public and private character displayed a mixture of good (for example, his defeat of the giant Goliath, 1 Samuel 17) and evil (as in his adultery with Uriah's wife, followed by his murder of Uriah, 2 Samuel 11). David's greatness lay in his fierce loyalty to God as Israel's military and political leader, coupled with his willingness to acknowledge his sins and ask for God's forgiveness (2 Samuel 12; see also Psalm 51). It was under David's leadership that the people of Israel were united into a single nation with Jerusalem as its capital city.
The collect for this day begins: "God of majesty, whom saints and angels delight to worship in heaven, we give thanks for David who, through the Psalter, gave Your people hymns to sing with joy in our worship on earth so that we may glimpse Your beauty..."