Here, a little bit of the history of authorship and background to this sefer, from the Otzar Midrashim, a scholarly encyclopedic work by that also contains the full text of many midrashim. After a page or so of discussion and analysis -- I strongly encourage you to read it all, even though I provided a short excerpt to the right -- it indeed gives the full text of this sefer Nevuat Hayeled, in a clear font and with some corrections. Much better than the printing of the stand-alone sefer, also at HebrewBooks.org.
If I may elaborate on why I am skeptical of the claim of this early authorship. First, it was a work "discovered" in the ruins of Yerushalayim by the fellow who then provided a perush on it -- much as the Zohar was discovered. (I am not sure if the Chidah actually ascribes authorship of Nevuat Hayeled to the commentator Rav Avraham HaLevi-- my surface reading of the summary to the right suggests that he does.) And anyway, this discovery was fairly late. And still later, a commentary on it also was claimed to be "found" when it was really the work of the one who "found" it, R' Yitzchak Satnow, who was a known maskil, and who apparently forged some of the approbations for his sefarim. R' Yitzchak Satnow also either recorded or made up the whole introduction cited here.
But that is not what really makes me doubt it. Rather, I have heard this precise story too many times.
It is amazing that a child is miraculously born (in that he needed to be prayed for), immediately begins to speak with secrets, is silent for a while, and at the age of 12 began to speak. This is the story of Nachman Ketoma. But it is also the story of:
- Ben Sirah
- The boy who saved Yosef, according to Koran and then Sefer Hayashar -- though this is the weakest.
For Merlin , his mother became pregnant from an incubus. She was accused of infidelity and baby Merlin spoke up to defend her. Merlin also gave all sorts of prophecies. Later, at about that same age, he contends with the wise men of King Vortigern and comes out ahead.
For Ben Sirah, in the quasi-pornographic medieval work The Alphabet of Ben Sirah, Yirmeyahu HaNavi is forced by evil men in a bathhouse to expel seed. He then immerses in the mikveh. His daughter, a virgin kohenes, immerses in that same mikveh in order to eat terumah and thus becomes pregnant. Baby Ben Sirah defends his mother of the charges of infidelity. Later, at about thirteen, he gives all the poetry and wise sayings in the Alphabet of Ben Sirah in a contest with a certain king's wise men.
The boy who saved Yosef was 11 months old, but miraculously spoke up to defend Yosef from charges of attacking Potifar's wife. And this is something to be expected from the Koran. He does not speak up later, at the age of 13.
But the idea of a magically speaking wise child giving prophecies or saying wise sayings is not unique. Rather, there is a trend. And so when I see something along the same lines, my first inclination is not to be awed by the miracle, but to see it as part of the made-up literary trend. The same reaction you would have if the backstory somehow was the same as that of Pinnochio.