Commentary for Exodus 16:15

מן הוא means this is something prepared for food, as in (Daniel 1:5) “And the king appointed (וימן) for them,”.

ויאמרו איש אל אחיו מן הוא, They said to one another it is manna, etc. We need to understand why this whole verse is necessary. Perhaps G'd caused them to say מן instead of מה, and this remained the name of this heavenly bread. This would correspond to a commentary on Psalms 46,9 in Berachot 7 where the word Shammot, desolation, is read instead as Shemot, names. According to the Talmud, G'd Himself named different phenomena in His world. The words כי לא ידעו, "for he (the people) did not know what it was," would be the reason why G'd had to supply the name. This may have been the reason the Israelites eventually lamented the nature of the manna. Perhaps the Israelites were very clever calling it מן as they realised (verse 31) that this word itself was something unusual and reflected the Spirit of G'd.

ויאמרו איש אל אחיו מן הוא, seeing that they did not know what it was; this is also the interpretation offered by Dunash in a book called “answers of Dunash,’ aimed at the commentary of Menachem, arguing that the end of the verse proves that this must be the meaning.