Ish hanikro baal haseior *1

R. Avrohom  (from) Troy writes in the Hakdama to his sefer,

he once dreamt on Friday night Parshas Beshalach ,that he sat at a table

with a very old man who had a white beard and long hair.

The old man asked him who was the greatest Navi and R.AT

answered “Moishe Rabeinu.” He then asked why did Moishe wait

to say the Shira until after Kreias Yam Suf. All other Nevi’im said

the Nevua before the happening.

R.AT answered that Moishe Rabeinu was concerned that the

Bnei Yisroel who weren’t strong in their emuna  won’t believe

him and won’t say the shira. He waited until after Krias Yam Suf.

Then it became Vayaminu Bahashem Uv’moishe avdo. Oz (when

they believed) Yoshir--.

"The old man accepted my answer with simcha."

R.AT continues that he always felt that the old man he saw in his

dream was Eliyahu  Hanavi.

One day he (R.AT) saw the tshuvas maharam who writes the
following story.*2

Rabeinu Efraim (baalei hatosfos). had a dream

that an old man who was hairy (long hair) had a hadras ponim

and long beard, served him a bowel of insects.

R. Efraim asked him why was he serving  him treifos. The old

man answered  that being He eats  Barbuta  fish  which is non kosher 

he deserves a bowel of sherotzim.  R. Efraim.said that the old man was

Eliyahu Hanavi and  from then on he refrained  eating Barbuta fish.

R.AT writes that after he saw this story and description of the old man

he became convinced that the old man he saw   (with the long hair) in his

dream was Eliyahu Hanavi

*1 piyut motzei shabbos

*2 Part of this story is is brought down in Hagahos Oshri (Rosh avoda zarah

Perek 3 Siman 41)