Or HaChaim on Genesis 49:20/אור החיים על בראשית מ״ט:כ׳

1 מאשר שמנה לחמו, "Asher's food will be rich, etc." Perhaps the emphasis is on the letter מ preceding the name אשר, and Jacob meant that Asher would be a "self-made" individual, i.e. tribe, producing all his wealth from within himself, either through his efforts or through his merit.