"And when God had removed him (Saul), He raised up for them David as King, to whom also He gave testimony and said "I have found David, the son of Jesse, a man after my own heart, who will do all my will. From this man's seed, according to the promise, God raised up for Israel a Savior-Jesus.’" Acts 13:22, 23; NKJ

Paul gives his listeners a limited but accurate summary of Israel's history, describing how the humanity of Jesus came through the line of David. The O.T. prophetic details of the coming Savior/Messiah fit only one person in human history--Jesus Christ of Nazareth. It seems like a contradiction that, with all of David's sin and wickedness, he could be a man after God's own heart. I have to believe His spirit was always eager to do the right thing, but his spirit was weak. One cannot read his Psalm of contrition and repentance (Ps.51) and miss the genuineness of his broken heart when he failed God.