For only Og king of Bashan remained of the remnant of giants; behold, his bedstead was a bedstead of iron; is it not in Rabbath of the children of Ammon? nine cubits was the length thereof, and four cubits the breadth of it, after the cubit of a man. Og king of Bashan remained - Og was the last king of the Amorites; his kingdom appears to have taken its name from the hill of Bashan; the country has been since called Batanaea.
Remnant of giants - Of the Rephaim. See on Deuteronomy 2:10 (note), Deuteronomy 2:11 (note).
His bedstead was - of iron - Iron was probably used partly for its strength and durability, and partly to prevent noxious vermin from harbouring in it.
Is it not in Rabbath, of the children of Ammon? - The bedstead was probably taken in some battle between the Ammonites and Amorites, in which the former had gained the victory. The bedstead was carried a trophy and placed in Rabbath, which appears, from 2 Samuel 12:26, to have been the royal city of the children of Ammon.
Nine cubits was the length - four cubits the breadth - Allowing the bedstead to have been one cubit longer than Og, which is certainly sufficient, and allowing the cubit to be about eighteen inches long, for this is perhaps the average of the cubit of a man, then Og was twelve feet high. This may be deemed extraordinary, and perhaps almost incredible, and therefore many commentators have, according to their fancy, lengthened the bedstead and shortened the man, making the former one-third longer than the person who lay on it, that they might reduce Og to six cubits; but even in this way they make him at least nine feet high.
On this subject the rabbins have trifled most sinfully. I shall give one specimen. In the Targum of Jonathan ben Uzziel on Numbers 21:33-35, it is said that "Og having observed that the camp of the Israelites extended six miles, he went and tore up a mountain six miles in its base, and put it on his head, and carried it towards the camp, that he might throw it on the Israelites and destroy them; but the word of the Lord prepared a worm, which bored a hole in the mountain over his head, so that it fell down upon his shoulders: at the same time his teeth growing out in all directions, stuck into the mountain, so that he could not cast it off his head. Moses, (who was himself ten cubits high), seeing Og thus entangled, took an axe ten cubits long, and having leaped ten cubits in height, struck Og on the ankle bone, so that he fell and was slain."
From this account the distance from the sole of Og's foot to his ankle was thirty cubits in length! I give this as a very slight specimen of rabbinical comment. I could quote places in the Talmud in which Og is stated to be several miles high! This relation about Og I suppose to be also an historical note added by a subsequent hand.