Do not go after other Gods

Backsliding: turning your heart away from the Lord

And the Lord was angry with Solomon, because his heart was turned away from the Lord, the God of Israel, who had twice come to him in a vision;
1 Kings 11:9

And had given him orders about this very thing, that he was not to go after other gods; but he did not keep the orders of the Lord.
1 Kings 11:10