2 Samuel 16:21

16:21 Ahithophel replied to Absalom, “Have sex with your father’s concubines whom he left to care for the palace. All Israel will hear that you have made yourself repulsive to your father. Then your followers will be motivated to support you.”

2 Samuel 20:3

20:3 Then David went to his palace in Jerusalem. The king took the ten concubines he had left to care for the palace and placed them under confinement. Though he provided for their needs, he did not have sexual relations with them. They remained in confinement until the day they died, living out the rest of their lives as widows.