Commentaries:
These verses serve two purposes: They are a reminder and a warning. He reminds them that He miraculously provided in their time of need due to the unusual circumstance He devised. The wider context shows this to be a warning that, despite all He did for them, His aid was ineffectual because they did not take His instruction to heart and do it. Consequently, they received God's grace—His gifts or favor—in vain.
John W. Ritenbaugh
Eating: How Good It Is! (Part One)