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...we can deduce that the inhabitants of Hijaz during Muhammad's time knew portions, at least, of 3 Enoch in association with the Jews. The angels over which Metatron becomes chief are identified in the Enoch traditions as the sons of God, the Bene Elohim, the Watchers, the fallen ones as the causer of the flood. In 1 Enoch, and 4 Ezra, the term Son of God can be applied to the Messiah, but most often it is applied to the righteous men, of whom Jewish tradition holds there to be no more righteous than the ones God elected to translate to heaven alive. It is easy, then, to imagine that among the Jews of the Hijaz who were apparently involved in mystical speculations associated with the merkabah, Ezra, because of the traditions of his translation, because of his piety, and particularly because he was equated with Enoch as the Scribe of God, could be termed one of the Bene Elohim. And, of course, he would fit the description of religious leader (one of the ahbar of the Qur'an 9:31) whom the Jews had exalted.
Source: G. D. Newby, A History Of The Jews Of Arabia, 1988, University Of South Carolina Press, p. 59.
Just because you haven't found an unbiased source that confirms this doesn't mean that it doesn't exist.