11 King David grew old. The years had caught up with him. Even though they piled blankets on him, he couldn't keep warm. 2 So his servants said to him, "We're going to get a young virgin for our master the king to be at his side and look after him; she'll get in bed with you and arouse our master the king." 3 So they searched the country of Israel for the most ravishing girl they could find; they found Abishag the Shunammite and brought her to the king. 4 The girl was stunningly beautiful; she stayed at his side and looked after the king, but the king did not have sex 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.