8 They were near the boulder at Gibeon when Amasa came their way. Joab was wearing a tunic with a sheathed sword strapped on his waist, but the sword slipped out and fell to the ground.

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.