When David arrived at his palace in Jerusalem, the king took the ten mistresses whom he had left behind to keep the palace in order and placed them in a separate house, providing for them under the care of a protective guard. He never visited them again, so they were under care until they died, living as if their husbands had died.
So the king left, taking his entire household with him except for ten mistresses, who were to keep the palace in order.
Ahithophel responded, "Go inside and have sex with your father's mistresses, whom he left to keep the palace in order. Then everyone in Israel will hear how your father has come to hate you and everyone who has joined you will be emboldened to act."