Charles Ellicott Commentary 2 Samuel 20:4

"Then said the king to Amasa, Call me the men of Judah together within three days, and be thou here present." — 2 Samuel 20:4 (ASV)

To Amasa. Thus, David begins the fulfilment of his promise of 2 Samuel 19:13. It proved an act of very doubtful expediency at this crisis.