Jamieson, Fausset and Brown on Deuteronomy 8:4

4. Thy raiment waxed not old upon thee, neither did thy foot swell, these forty years--What a striking miracle was this! No doubt the Israelites might have brought from Egypt more clothes than they wore at their outset; they might also have obtained supplies of various articles of food and raiment in barter with the neighboring tribes for the fleeces and skins of their sheep and goats; and in furnishing them with such opportunities the care of Providence appeared. But the strong and pointed terms which Moses here uses (see also De 29:5) indicate a special or miraculous interposition of their loving Guardian in preserving them amid the wear and tear of their nomadic life in the desert. Thirdly, Moses expatiated on the goodness of the promised land.