Amasa went before them; having gathered some forces, and given due orders for the rest to follow him, he returned to Jerusalem, and by the king's command went after those mentioned 2 Samuel 20:7; and being come up to them at the place where they waited for him, he put himself into the head of Joab's men, and the Cherethites and the Pelethites, and such as he had brought along with him, and marched before them as their chief and general. Girded unto him, after the manner of travellers and soldiers. As he went forth to meet and salute Amasa, who was coming towards him to do him honour. It fell out; things having (it is likely) been so contrived by Joab, that upon the least motion of his body his sword should drop out, and he might take it up without raising Amasa's suspicion.
Related Commentaries of 2 Samuel 20:8
2 Samuel 20:8
8 When they were at the great stone which is in Gibeon, Amasa went before them. And Joab's garment that he had put on was girded unto him, and upon it a girdle with a sword fastened upon his loins in the sheath thereof; and as he went forth it fell out.