R. Yehudah understands this as meaning: Are you of the vine of Sodom or the planting of Amorah! Are you not of a holy planting? But they turned into (the opposite). As it is written (Jeremiah 2:21) "I had planted you from a choice vine, entirely of the seed of truth. How, then, have you turned yourself into an alien vine before Me!"
(Devarim, Ibid.) "Their grapes are grapes of gall ('rosh')": You are sons of the first man ("rishon," as in "rosh"), who decreed death upon all his descendants who came after him, until the end of all the generations.