Why not to say Parshas Ha'mon
Shulchan Aruch ( O.Ch 1: 23) It is good to say Parshas Ha'mon.
(Levush) So that you will believe , Parnasa is Hashgacha Peratis
The Aruch Hashulchan writes, Our Minhag is not to say it.
There is no mention of Parshas Ha’mon in Shas
The Derisha claims there is a Yerushalmi (Brachos) that speaks
about the Segula of Parshas Ha’mon. The Aruch Hashulchan writes
he couldn’t find this Yerushalmi .
He continues , The reason for not saying Parshas Ha’mon is
a)The Parsha mentions numerous times the Bnai Yisroels complaints
of not having food.
b)the complaints on the Manna.
c)The Midrash writes Hashem said “I don’t need not your
complaints and not your praises." (on the Manna)
If the sole purpose of saying the Parsha,is only to have the Segulah
Of Parnasah, The Rambam might consider it Kefirah. "They make
The Divrei Torah a Refuas Haguf and it isn’t but a Refuas Hanefesh"
(Hl. Avoda Zarah (Perek 11)