Source for saying Parshas Hamon?

Question

There is a segulo for parnoso which is to read Parshas Hamon every day after davening. I have seen people "quote the Yerushalmi" for this but I have been unable to locate its source. Can anyone shed some light on the origins of this segulo?

Answer 1

The oldest source I found was the Sefer haManhig (Shabbat 44) by R' Avraham ben Nathan:

בסוף יומא ירושלמי – כל האומר פרשת המן בכל יום, מובטח לו, שאין מזונותיו נחסרין.‏

At the end of Yerushalmi Yoma [it is said] – Whoever says the chapter of the manna each day, it is assured for him that he wouldn't lack his sustenance.

R' Bachya mentions a similar teaching in Beshalach 16 (end of top left column).

The custom is also brought by the Tashbetz (256), disciple of the Maharam of Rothenburg:

ירושלמי – כל האומר פרשת המן בכל יום, מובטח הוא שלא יתמעטו מזונותיו, ואני ערב.‏
[It is written in the] Yerushalmi – Whoever says the chapter of the manna each day, he is assured that his sustenance will not decrease, and I guarantee.

If you check the comments in the side notes, you can see that this custom is brought by many other rabbis, but they couldn't find its source in the Yerushalmi either. The Arukh Hashulchan 1:24 copies the words of the Perishah (fourth row from top), but he also mentions that he was unable to find it. Many authors say therefore that we don't have that version of the Yerushalmi now in our hands that our rabbis had in the past.*

^{* I've found this article a particularly useful source.}

Answer 2

Dov Baer Ratner discusses this issue in Ahavat Tzion vYrushalayim on Yoma, pg. 103-4. It seems that the Sefer haManhig (an obscure rishon) had a version of y. Yoma that continued a bit further, including this and other statements. Most are found elsewhere in the Yerushalmi, but not this one. None of the Geonim seem to have had this text, nor any of the mainstream rishonim. It has been embraced now by a millenium of mystics but personally I do not think it likely that this was ever a real Yerushalmi. It fits much better into 13th century (when it was first quoted) Kabbalistic thinking that it does into the Yerushalmi, and some of those Kabbalists were notorious forgers.