He tarried - The cause of Amasa's delay is not stated. It may have been the unwillingness of the men of Judah to place themselves under his orders, or it may have been caused by a wavering or hesitation in loyalty. This last is evidently insinuated in 2 Samuel 20:11, and no doubt this was the pretext, whether grounded in fact or not, by which Joab justified the murder of Amasa before David.

So Amasa went to assemble the men of Judah,.... To gather, them together out of their several tribes, and bring them to Jerusalem:

but he tarried longer than the set time which he had appointed him: than the three days; whether this was owing to the remissness of Amasa, or the unwillingness of the people to serve under him, who had been Absalom's general in the late rebellion, or not having time sufficient allowed him, is not certain.

But when Amasa stayed out beyond the time fixed for the execution of the royal commission (the Chethib וייחר is the Piel וייחר, whilst the Keri is either the Hiphil ויּוחר, or the imperfect Kal of יחר equals אחר, cf. תּחז, 2 Samuel 20:9, and is quite unnecessary), probably because the men of Judah distrusted him, and were not very ready to respond to his summons, David said to Abishai, "Now will Sheba the son of Bichri be more injurious (more dangerous) to us than Absalom. Take thou the servants (soldiers) of thy lord and pursue after him, lest he reach fortified cities, and tear out our eye," i.e., do us a serious injury. This is the correct explanation given by Bttcher, who refers to Deuteronomy 32:10 and Zechariah 2:12, where the apple of the eye is the figure used to signify the most valuable possession; for the general explanation, "and withdraw from our eye," cannot be grammatically sustained.

So Amasa went to assemble the men of Judah: but he tarried longer than the set time which he had appointed him.

20:5 Tarried - Either, because the people being wearied out by the late war, were not forward to engage in another: or because the soldiers had more affection to Joab, than to their new general.

Assemble: Heb. Call

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.