Deuteronomy 8:3

God humbled the Israelites by leaving them to suffer hunger from the want of food, and then supplying them with food in a miraculous manner. They were thus taught that their life depended wholly on God, who could, by his own creative power, without any of the ordinary means, provide for the sustaining of their life. And fed thee with manna (cf. Exodus 16:15 ). It is in vain to seek to identify this with any natural product. It was something entirely new to the Israelites—a thing which neither they nor their fathers knew; truly bread from heaven, and which got from them the name of manna or man , because, in their wondering ignorance, they knew not what to call it, and so they said one to another, Man hoo? ( מָן הוּא ), What is it? and thenceforward called it man . That he might make thee know , etc. "Bread," which the Jews regarded as "the staff of life," stands here, as in other places, for food generally; and the lesson taught the Israelites was that not in one way or by. one kind of means alone could life be sustained, but in the absence of these God could, by his own fiat, provide for the sustenance of his children. Every word —literally, all , everything whatever— that proceedeth out of the mouth of the Lord , i.e. all means which God has by his word provided, or by his word can provide, for the sustenance of life. So our Lord cites this passage in replying to the tempter, who had suggested that if he was the Son of God he might relieve himself from the pangs of hunger by commanding the stones which lay around to become bread. Our Lord's reply to this is virtually." I have this power, and could use it, but I will not; for this would imply impatience and distrust of God, who has engaged to sustain the life of his servants, and who can, by the mere word of his mouth, by his creative will, provide in an extraordinary way for the sustenance of life when the ordinary means of life are wanting." "Jesus means to say, ' I leave it with God to care for the sustaining of my life, and I will not arbitrarily and for selfish ends help myself by a miracle'" (De Wette, note on Matthew 4:4 ; see also Meyer on the place).