This is a case of something that is actually very common. The New Testament is quoting the Old Testament out of context. Here the leap from “whatever God says” to “God’s words” is explained by the expression “motza of God’s mouth,” which normally means “whatever God says” but which, out of context, might mean “God’s actual words.” A passage that started off by asserting that one can live on any food that God declares edible morphed into a statement about living on God’s very declarations.
