Treasury of Scripture Knowledge
And David came to his house at Jerusalem; and the king took the ten women his concubines, whom he had left to keep the house, and put them in ward, and fed them, but went not in unto them. So they were shut up unto the day of their death, living in widowhood.
2 Samuel 15:16
So the king and all the members of his royal court set out on foot, though the king left behind ten concubines to attend to the palace.
2 Samuel 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."
so he imprisoned them in the house of the captain of the guard in the same facility where Joseph was confined.