1 Kings 15:3

And he walked in all the sins of his father, which he had done before him: and his heart was not perfect with the LORD his God, as the heart of David his father.

Heart was not perfect with the Lord, х shaaleem (H8003)] - at peace, in harmony with.

As the heart of David - (cf. 1 Kings 11:4; 1 Kings 14:22). He was not positively bad at first, because it appears (1 Kings 15:15) that he had done something to restore the pillaged treasures of the temple. This phrase contains a comparative reference to David's heart. His doing that which was right in the eyes of the Lord (1 Kings 15:5) is frequently used in speaking of the kings of Judah, and means only that they did or did not do that which, in the general course and tendency of their government, was acceptable to God. It furnishes no evidence as to the lawfulness or piety of one specific act.