To anyone familiar with talmudic tales, Bessarion’s story cannot help bringing to mind another, much earlier episode of contested religious leadership. It seems the sage Rabban Gamliel, the nasi or religious head of post-Temple Jewry, was temporarily relieved of his position on account of what his colleagues considered a heavy-handed exercise of authority. The rabbis’ ultimate choice of a successor was Elazar ben Azaryah, a brilliant scion of prestigious lineage. But Elazar, too, had a flaw, though the opposite of Bessarion’s: being only eighteen years old, he did not yet have the full growth of facial hair expected of a Jewish religious leader. Fortunately, according to the Talmud, a miracle was wrought overnight, and Elazar awoke to find himself the owner of a long white beard. The story concludes that he was wont to say of himself: “Behold, I am akin to a man of seventy years.”This sadly is not correct. Let's just get this straight. There is no miracle of the overnight beard growth in rabbinic literature.
In the deposition narrative we have two variants on the legend that Eleazar's hair turned grey.
Yer. Ber. 4:1 says:See my doctoral thesis from 1977, pp 148 ff. Eleazar's hair or beard turned grey, but nowhere is there a narrative of miraculous beard growth in this episode.
U. They went and appointed (mynw) R. Eleazar b. Azariah to the academy (yšybh).
V. He was sixteen years old and all his hair turned grey (ntml' kl r'šw sybyt).
B. Ber. 27b-28a:
FF. She said to him, ``You have no white hair.''
GG. On that day he was eighteen years old. A miracle befell him and eighteen rows of his hair turned white.
Postscript: After all these years I must say that the Bavli version seems rather demeaning to Eleazar's wife. Portrayal of her concern with lack of grey hair seems awfully superficial at best.
Bottom line. The Commentary editors let into their esteemed journal a sermon with an erroneous account of a rabbi sprouting a beard overnight.