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

[215] By these words the people were struck as it were by all iron hammer, and were so grieved at the words, as if they had already felt the effects of them; and they had great indignation at the king; and all cried out aloud, and said, "We will have no longer any relation to David or his posterity after this day." And they said further, "We only leave to Rehoboam the temple which his father built;" and they threatened to forsake him. Nay, they were so bitter, and retained their wrath so long, that when he sent Adoram, which was over the tribute, that he might pacify them, and render them milder, and persuade them to forgive him, if he had said any thing that was rash or grievous to them in his youth, they would not hear it, but threw stones at him, and killed him. When Rehoboam saw this, he thought himself aimed at by those stones with which they had killed his servant, and feared lest he should undergo the last of punishments in earnest; so he got immediately into his chariot, and fled to Jerusalem, where the tribe of Judah and that of Benjamin ordained him king; but the rest of the multitude forsook the sons of David from that day, and appointed Jeroboam to be the ruler of their public affairs. Upon this Rehoboam, Solomon's son, assembled a great congregation of those two tribes that submitted to him, and was ready to take a hundred and eighty thousand chosen men out of the army, to make an expedition against Jeroboam and his people, that he might force them by war to be his servants; but he was forbidden of God by the prophet [Shemaiah] to go to war, for that it was not just that brethren of the same contry should fight one against another. He also said that this defection of the multitude was according to the purpose of God. So he did not proceed in this expedition. And now I will relate first the actions of Jeroboam the king of Israel, after which we will relate what are therewith connected, the actions of Rehoboam, the king of the two tribes; by this means we shall preserve the good order of the history entire.