(Exodus 20:22) "Do not build them gazith": "gazith" is "gezuzoth" (hewn,) iron having been lifted upon them. R. Nathan says: I might think that if one built two stones (into the altar) upon which iron had been lifted (that) the entire altar is unfit, it is, therefore, written "Do not build them hewn" — They are unfit, but not the entire altar.