Isaiah 9:20

And one snatched on the right hand and was hungry (still) and devoured on the left hand and they were not satisfied, &c.

every man the flesh of his own arm The image would be that of men maddened with hunger and gnawing their own flesh. The words are reproduced exactly, with the omission of a single letter, in Jeremiah 19:9, which gives the sense "every man the flesh of his neighbour." It might be better to assimilate the text here to that reading, since it is the "cruelty of rival factions" that seems to be described.