Albert Barnes Commentary 1 Kings 1:15

"And Bath-sheba went in unto the king into the chamber: and the king was very old; and Abishag the Shunammite was ministering unto the king." — 1 Kings 1:15 (ASV)

Into the chamber - The “bed-chamber” or “inner chamber.” Abishag was an impartial witness present, who heard all that Bathsheba said to David.