Flavius Josephus, Antiquities of the Jews
William Whiston, A.M., Ed.

[258] NOW those Hebrews that had been With Absalom, and had retired out of the battle, when they were all returned home, sent messengers to every city to put them in mind of what benefits David had bestowed upon them, and of that liberty which he had procured them, by delivering them from many and great wars. But they complained, that whereas they had ejected him out of his kingdom, and committed it to another governor, which other governor, whom they had set up, was already dead, they did not now beseech David to leave off his anger at them, and to become friends with them, and, as he used to do, to resume the care of their affairs, and take the kingdom again. This was often told to David. And, this notwithstanding, David sent to Zadok and Abiathar the high priests, that they should speak to the rulers of the tribe of Judah after the manner following: That it would be a reproach upon them to permit the other tribes to choose David for their king before their tribe, "and this," said he, "while you are akin to him, and of the same common blood." He commanded them also to say the same to Amasa the captain of their forces, That whereas he was his sister's son, he had not persuaded the multitude to restore the kingdom to David; that he might expect from him not only a reconciliation, for that was already granted, but that supreme command of the army also which Absalom had bestowed upon him. Accordingly the high priests, when they had discoursed with the rulers of the tribe, and said what the king had ordered them, persuaded Amasa to undertake the care of his affairs. So he persuaded that tribe to send immediately ambassadors to him, to beseech him to return to his own kingdom. The same did all the Israelites, at the like persuasion of Amasa.