Deuteronomy 8:3

And He humbled thee and let thee hunger, and fed thee with the manna which thou knewest not, nor thy fathers had known, that He might make thee to know that man liveth not by bread only, but by all that is created by the Word of the Lord doth man live.

He afflicted you on the road.

He famished you before the coming of the manna . — or, more likely, He “famished” needs other than hunger.

The word they knew [Hebrew: yadun] ends with a nun , like “They poured out [Hebrew: ṣaqun] a silent prayer” [Isaiah 26: 16], and also “they camped [Hebrew: yaḥanun] on the other side of כ Arnon” [Judges 11: 18]. ...

The word to inform you is in the infinitive form.

the bread means that which a man is accustomed to.

that emanates from the mouth of God i.e., what He decrees. Compare, “as the word went out of the king’s mouth” [Esther 7: 8]. The sense of the verse is that Man does not live from just bread, but rather, from the energy that it contains — and could live just as well from energy that comes to us from Heaven, through the Divine decree (this is the meaning of emanates from the mouth of God). The proof is that although you did not eat bread, you nevertheless lived [cf. 29: 5].

AND HE FED THEE WITH MANNA, WHICH THOU KNOWEST NOT, NEITHER DID THY FATHERS KNOW. The purport thereof is that you did not know about the manna that you could live by it for many years, nor did such a tradition reach you from your fathers. Or he [Moses] may be saying that He has done with you this great kindness which your holy fathers [i.e., the patriarchs] did not obtain, for, although they walked after Him wherever He commanded them, as is stated, Get thee out of thy country, and from thy kindred, and from thy father’s house, yet their eminence did not suffice that He should support them with the corn of heaven as He did for you. And so the Rabbis have said in the Midrash Bamidbar Sinai Rabbah: “Because of the merit of Moses you ate the manna that your holy fathers did not see, as it is said, neither did thy fathers know.” And he explained that He did this in order to inform them that it is He Who preserves man with whatever He decrees, and if so observe His commandments, and live.
It is possible to explain that the expressions And He afflicted thee, and suffered thee to hunger, and fed thee with manna refer to different subjects. He is stating that He afflicted you when you travelled in the wilderness for forty years, similar to the verse, He afflicted my strength in the way, [meaning that travel drains the strength]. And He suffered thee to hunger, at the beginning [of the journey in the wilderness] as the people said, to kill this whole assembly with hunger, and afterwards He fed you with the manna to make you aware that by every word that proceedeth out of the mouth of the Eternal doth man live. So also, Who fed thee in the wilderness with manna, which thy fathers knew not, telling them of the miracle that was done to them. And the expression that He might afflict thee [further in Verse 16] reverts to that which he said [in the preceding Verse 15], Who led thee through the great and dreadful wilderness, wherein were serpents, fiery serpents, and scorpions, and draught etc., Verse 15. In other words, since according to Ramban’s interpretation before us, the expression that He might afflict thee refers not to the manna but to the journey through the wilderness, then we must also say that the expression that He might afflict thee in Verse 16 following the subject of the manna is to be interpreted as reverting to the beginning of Verse 15, where the subject of the wilderness is mentioned. But that which He said in the section of the manna, that I may, try them, whether they will walk in My law or not means that I will provide them their needs and fulfill their request and [then] see if they will hearken to Me when goods increase. This is in consonance with the plain meaning of Scripture, but the first interpretation is true and correct.

ויענך, “He afflicted you, etc.” a reference to the tedium of the journey. Compare Psalms 102,24: ענה בדרך כוחי קצר ימי, “He drained my strength while on the way; He shortened my days.”

וירעיבך, “He starved you;” by giving you only enough food for the same day. This is the meaning of the term רעבון; our sages formulated it thus: “one cannot compare a person with bread in his pocket to a person who has nothing in his pocket.” [One can’t have more than one day’s supply in one’s pocket. Ed.] (Compare Talmud tractate Yuma folio 74.)

למען הודיעך כי לא על הלחם לבדו יחיה האדם, “in order to make you realise that man does not live by bread alone.” כי על כל מוצא פי ה' יחיה האדם, “but by everything that proceeds out of the mouth of the Lord, does man live.” All His decrees and commandments emanating from Him are what enable man to live. They enable you to live on earth and in your afterlife.