8 When they were at the great stone which is in Gibeon, Ama'sa came to meet them. Now Jo'ab was wearing a soldier's garment, and over it was a girdle with a sword in its sheath fastened upon his loins, and as he went forward it fell out.

Matthew Henry's Commentary on 2 Samuel 20:8

Commentary on 2 Samuel 20:4-13

(Read 2 Samuel 20:4-13)

Joab barbarously murdered Amasa. The more plot there is in a sin, the worse it is. Joab contentedly sacrificed the interest both of the king and the kingdom to his personal revenge. But one would wonder with what face a murderer could pursue a traitor; and how, under such a load of guilt, he had courage to enter upon danger: his conscience was seared.