Albert Barnes Commentary 2 Samuel 3:20

"So Abner came to David to Hebron, and twenty men with him. And David made Abner and the men that were with him a feast." — 2 Samuel 3:20 (ASV)

Twenty men - These were undoubtedly his official suite as Ishbosheth’s envoy to conduct Michal to David, but they were aware of and consented to his intrigue with David. It is remarkable that not a word is said about the meeting of David and Michal.