Rashi on Deuteronomy 8:4/רש"י על דברים ח׳:ד׳

1שמלתך לא בלתה THY RAIMENT DID NOT WEAR OUT — the clouds of Divine Glory used to rub the dirt off their clothes and bleach them so that they looked like new white articles, and also, their children, as they grew, their clothes grew with them, just like the clothes (shell) of a snail which grows with it (cf. Shir HaShirim Rabbah 4:11; Yalkut Shimoni on Torah 850).

2לא בצקה This means: [AND THY FOOT] DID NOT SWELL like dough (בצק), as is usual with those who walk barefoot — that their feet become swollen.