8:3 manna, which you did not know. The initial giving of manna is mentioned in Ex. 16:15, its cessation in Josh. 5:12. God chose to sustain His people in the wilderness by a means previously unknown to them. Through this miraculous provision God humbled the people (by challenging their self-sufficiency) and tested their obedience (v. 16; cf. Ex. 16:16–30).
every word that comes from the mouth of the Lord. Even more basic to life than physical food is the sustaining word of God (Heb. 1:3).