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

[96] When matters were come to this state, Og, the king of Gilead and Gaulanitis, fell upon the Israelites. He brought an army with him, and in haste to the assistance of his friend Sihon: but though he found him already slain, yet did he resolve still to come and fight the Hebrews, supposing he should be too hard for them, and being desirous to try their valor; but failing of his hope, he was both himself slain in the battle, and all his army was destroyed. So Moses passed over the river Jabbok, and overran the kingdom of Og. He overthrew their cities, and slew all their inhabitants, who yet exceeded in riches all the men in that part of the continent, on account of the goodness of the soil, and the great quantity of their wealth. Now Og had very few equals, either in the largeness of his body, or handsomeness of his appearance. He was also a man of great activity in the use of his hands, so that his actions were not unequal to the vast largeness and handsome appearance of his body. And men could easily guess at his strength and magnitude when they took his bed at Rabbath, the royal city of the Ammonites; its structure was of iron, its breadth four cubits, and its length a cubit more than double thereto. However, his fall did not only improve the circumstances of the Hebrews for the present, but by his death he was the occasion of further good success to them; for they presently took those sixty cities, which were encompassed with excellent walls, and had been subject to him, and all got both in general and in particular a great prey.