When King David was old and well advanced in years, he could not keep warm even when they put covers over him.
References for 1 Kings 1:1
So his servants said to him, "Let us look for a young virgin to attend the king and take care of him. She can lie beside him so that our lord the king may keep warm."
Then they searched throughout Israel for a beautiful girl and found Abishag,1 a Shunammite,2 and brought her to the king.
References for 1 Kings 1:3
The girl was very beautiful; she took care of the king and waited on him, but the king had no intimate relations with her.