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

[514] Whereupon the zealots, out of the dread they were in of his attacking them, and being willing to prevent one that was growing up to oppose them, went out against him with their weapons. Simon met them, and joining battle with them, slew a considerable number of them, and drove the rest before him into the city, but durst not trust so much upon his forces as to make an assault upon the walls; but he resolved first to subdue Idumea, and as he had now twenty thousand armed men, he marched to the borders of their country. Hereupon the rulers of the Idumeans got together on the sudden the most warlike part of their people, about twenty-five thousand in number, and permitted the rest to be a guard to their own country, by reason of the incursions that were made by the Sicarii that were at Masada. Thus they received Simon at their borders, where they fought him, and continued the battle all that day; and the dispute lay whether they had conquered him, or been conquered by him. So he went back to Nain, as did the Idumeans return home. Nor was it long ere Simon came violently again upon their country; when he pitched his camp at a certain village called Thecoe, and sent Eleazar, one of his companions, to those that kept garrison at Herodium, and in order to persuade them to surrender that fortress to him. The garrison received this man readily, while they knew nothing of what he came about; but as soon as he talked of the surrender of the place, they fell upon him with their drawn swords, till he found that he had no place for flight, when he threw himself down from the wall into the valley beneath; so he died immediately: but the Idumeans, who were already much afraid of Simon's power, thought fit to take a view of the enemy's army before they hazarded a battle with them.