11 King David was now very old, and no matter how many blankets covered him, he could not keep warm. 2 So his advisers told him, "Let us find a young virgin to wait on you and look after you, my lord. She will lie in your arms and keep you warm." 3 So they searched throughout the land of Israel for a beautiful girl, and they found Abishag from Shunem and brought her to the king. 4 The girl was very beautiful, and she looked after the king and took care of him. But the king had no sexual relations with her.
Matthew Henry's Commentary on 1 Kings 1:1-4
Commentary on 1 Kings 1:1-4
(Read 1 Kings 1:1-4)
We have David sinking under infirmities. He was chastised for his recent sins, and felt the effects of his former toils and hardships.