What was it that cause David to be the man after hid God own Heart, from Samuel times to when David became King of Israel?

TNDL: "EL-ELYON WAYS AND THOUGHTS ARE HIGHER THAT MEN OF EARTHLY WISE MEN WAYS AND THOUGHTS! THEREFORE, WHAT THE LORD SAYS, IS WHAT IT IS, AND NO MAN OR WOMAN, SHOULD TRY AND CHANGE, ACCORDING TO THEIR OWN UNDERSTANDING AND MEANING."

Born in 907 BC, David reigned for 40 years as Israel's second king, handpicked by the Lord Himself because David proved to be a man after the heart of God. ... desert oasis of Ein Gedi is the location of the dramatic meeting of King Saul and David in 1 Samuel 24. David fled south and hid in a cave in the desert at Ein Gedi.