2 Samuel 20:8

The great stone which is in Gibeon. Gibeon is situated in the mountains of Ephraim, in the tribe of Benjamin, northwest of Jerusalem. The great stone was probably some isolated rock well known in the neighbourhood. Amasa went before them; Hebrew, Amasa came before them; that is, came in view with the levy of men he had raised in Judah. And Joab's garment, etc.; more correctly, and Joab was girded with his military coat as his garment, and over it was the strap of his sword in its sheath, and it (masculine, equivalent to "the sheath") came out, and it (feminine, equivalent to "the sword") fell. This change of gender is very harsh, and has caused the Authorized Version to apply the masculine verb to Joab, and translate, and as he went forth it fell; but a very slight change, supported by the Septuagint, gives us a more satisfactory sense, namely, and it ( the sword ) came out and fell. It is generally assumed that all this was arranged beforehand on Joab's part, who had so placed his sword that he could shake it out of the sheath. More probably it was an accident, of which he took instant advantage. He had felt that his position was insecure, and that if David had the support of Amasa, and a powerful band of the men of Judah at Jerusalem, he would probably order his execution for slaying Absalom; and Amasa would carry out the command willingly enough, as he thereby would secure the high position offered him. We know David's feelings towards Joab from his dying command to Solomon ( 1 Kings 2:5 ), and probably he had given various indications of his deep seated resentment. Joab, therefore, determined to stop Amasa's growth in power, and also to give David a rough lesson. And this accident gave him an early opportunity, which he used with ruthless energy.