Albert Barnes Commentary Acts 13:22

"And when he had removed him, he raised up David to be their king; to whom also he bare witness and said, I have found David the son of Jesse, a man after My heart, who shall do all My will." — Acts 13:22 (ASV)

And when he had removed him. This was done because Saul rebelled against God by sparing the sheep, oxen, and valuable property of Amalek, along with Agag the king, when he was commanded to destroy everything (1 Samuel 15:8–23). Saul was put to death in a battle with the Philistines (1 Samuel 22:1–6). The phrase "when he removed him" probably refers to Saul's rejection as a king, and not to his death. This is because David was anointed king before Saul's death and almost immediately after Saul's rejection due to his rebellion in the matter of Amalek (See 1 Samuel 6:12–13).

He gave testimony. He bore witness (1 Samuel 13:14).

I have found David, etc. This is not quoted literally but contains the substance of what is expressed in various places (Compare 1 Samuel 13:14 with Psalm 89:20 and 1 Samuel 16:1, 12).

A man after mine own heart. This expression is found in 1 Samuel 13:14. The connection shows that it simply means a man who would not be rebellious and disobedient as Saul was, but would do God's will and keep His commandments. This refers, doubtless, to David's public character as a king rather than to his private character.

It means that he would make the will of God the great rule and law of his reign, in contrast to Saul, who, as a king, had disobeyed God. At the same time, it is true that David's prevailing character as a pious, humble, and devoted man was that he was a man after God's own heart and was beloved by Him as a saint and a holy man.

He had faults; he committed sin—but who is free from it? He was guilty of great offenses, but he also showed, to an equally eminent degree, repentance (Psalms 51). Not less in his private than in his public character did he show those traits that were prevailingly in accord with the heart—that is, the earnest desires—of God.

Which shall fulfil all my will. Saul had not done it. He had disobeyed God in a case where he had received an express command. The characteristic of David would be that he would obey the commands of God. That David did this—that he maintained the worship of God, opposed idolatry, and sought to promote universal obedience to God among the people—is expressly recorded of him (1 Kings 14:8–9): And thou [Jeroboam] hast not been as my servant David, who kept my commandments and who followed me with all his heart, to do that only which was right in mine eyes. etc. (See also 1 Kings 15:3, 5).