It wasn’t enough that David was sick in bed, but he also had to deal with treachery among his own family and friends, including men like Ahithophel, his official counselor, who sided with Absalom. Ahithophel was Bathsheba’s grandfather (2 Sam. 11:3; 23:34) and hated David for what he did to her and to her husband Uriah. These false friends visited the king and lied to him (“We hope you’ll get well soon”), but they really wanted David to die and even plotted against him. But if Absalom became king, that would be the end of the Davidic dynasty, for Absalom had no son (2 Sam. 18:18). God promised David that his descendants would sit on the throne of Israel forever (2 Sam. 7:11–16), a promise ultimately fulfilled in Jesus Christ (Luke 1:31–33). David was gifted at reading people (2 Sam. 14:17–20) and knew the truth.
Jesus used verse 9 when referring to the traitor Judas (John 13:18–19; and see 55:12–14; 69:25; 109:8; Matt. 26:63; Mark 14:18; Luke 22:21; Acts 1:16–20). Note that our Lord didn’t quote the phrase “whom I trusted” from verse 9, for He knew that Judas had no saving faith (John 6:70–71). This psalm opens with a statement about the poor, and Judas tried to identify himself with the poor (John 12:4–6; 13:26–30). David’s enemies wanted the king’s name to perish, but it was Judas who destroyed a good name—“Judah,” which means “praise.” We call our sons David but we would never call a son Judas. (See 2 Sam. 16:15–17: for Ahithophel’s part in the rebellion.) The phrase “lifted up his heel” pictures a deceptive and underhanded attack, but see Joshua 10: and Romans 16:20.