What does it mean that David was a man after God's own heart?

from the old testament

• The verse where the expression "a man after God's own heart" is found is 1 Samuel 13:14, which reads, “But now [Saul’s] kingdom shall not continue. The LORD has sought out a man after his own heart, and the LORD has commanded him to be prince over his people, because [Saul has] not kept what the LORD commanded ....” God took the kingdom away from Saul and looked for the replacement king (1 Samuel 15:26–28).
• To replace Saul, God was searching out His own choice for king. This is in contrast to Saul, who had been Israel’s choice (1 Samuel 8:5; 9:2). They had looked on the outside and saw that he was tall and handsome, and based their choice on that. While God had not been happy that they chose Saul, He allowed it (1 Samuel 8:7–9). Unlike Israel, God did not look for a king by looking on the outside. Instead, He considered people’s hearts (1 Samuel 16:7). So, when He chose David, it was not based on his external characteristics but on his character.
• But some go wrong when they take 1 Samuel 13:14 to refer specifically to David’s character. God did not choose David because he was perfectly, or even largely, righteous. Rather, God was expressing that David was His choice in contrast to Israel’s choice of Saul.
• Historically, while David was indeed righteous at many points in his life, he also sinned at several points, even badly at one point by committing adultery and murder (2 Samuel 11). Understanding 1 Samuel 13:14 as referring primarily to God’s choice rather than David’s character helps us guard against elevating David’s character too high.
• However, by choosing David after looking inside him, God was saying something about David’s character. While he was not perfect, his heart was a humble, God-fearing one. In contrast to Saul, who sinned and responded pridefully to rebuke (1 Samuel 15:20–21, 24), David was filled with sorrow and repentance (i.e., Psalm 51). Therefore, God’s choice took David's repentant and submissive character into account.

from the new testament

• Helping us understand what 1 Samuel 13:14 meant is Acts 13:22, which reads, “And when [God] had removed [Saul], he raised up David to be their king, of whom he testified and said, ‘I have found in David the son of Jesse a man after my heart, who will do all my will.’” By adding “who will do all my will,” Paul was summarizing the 1 Samuel 13 context, where Saul was not characterized as going in God’s will, in contrast to David, albeit imperfectly. Paul’s interpretation helps us to understand that David was God’s choice because God knew that David would obey.

implications for today

Consider your own heart and its willingness to do what God desires. Before God created the world, He prepared specific things for each of us to do (Ephesians 2:10). However, to do them, we need to be surrendered to Him and have humble, serving hearts. To accomplish this, when God saved us through Christ, He changed our hearts (Ezekiel 36:26). That doesn’t mean we are perfect when we are saved, but God, in saving us, freed our hearts from slavery to sin, giving us the ability to obey and serve Him (Romans 6:18).

As believers, then, we are to cultivate humble, willing hearts. What helps us do this? Studying and memorizing Scripture so our thinking is transformed to be more like Christ (Romans 12:2); walking in the Spirit, displaying His fruit and being like Christ; and practicing other spiritual disciplines such as prayer, attending church, and serving other believers. As we do, we become more like Christ, and our hearts move more and more in alignment with God’s.

Like with David, God chose us of His own will. He did not choose us because we already had hearts like His but so He could change us, eventually making us more like Him!