And they tempted God in their heart. This is the provocation of which mention is made in the preceding verse. Not that it was unlawful for them simply to ask food, when constrained to do so by the cravings of hunger. Who can impute blame to persons, when being hungry, they implore God to supply their necessities? The sin with which the Israelites were chargeable consisted in this, that not content with the food which He had appointed them, they gave loose reins to their lusts. He, at that time, had begun to feed them with manna, as we shall again see by and by. It was their loathing of that sustenance which impelled them eagerly to desire new food, as if they disdained the allowance assigned them by their heavenly Father. This is what is meant when it is said that they asked food for their soul [1] They were not reduced to the necessity of asking it by hunger; but their lust was not satisfied with living on the provision which God had appointed for them. On this account, it is declared, that they tempted God, overpassing, as they did, the bounds within which he had limited them. Whoever, undervaluing and despising the permission or license which He grants, gives full scope to his own intemperate lust, and desires more than is lawful, is said to tempt God. He acts as if he would subject Him to his own caprice, or questioned whether He could do more than he is pleased really to do. God has power to accomplish whatever he wills; and assuredly, the person who would separate the power of God from his will, or represent him as unable to do what he wills, does all he can to rend him in pieces. Those are chargeable with doing this, who are set upon trying whether he will grant more than he has given them permission to ask. That, therefore, the lust of the flesh may not stir us up to tempt him, let us learn to impose a restraint upon our desires, and humbly to rest contented within the limits which are prescribed to us. If the flesh is allowed to indulge itself without control, we will not be satisfied with ordinary bread, but will often, and in many ways, murmur against God.

Footnotes

1 - The word nphs, nephesh, for soul, has great latitude of signification. It sometimes signifies the sensitive or animal appetites, as in this passage. The people had their wants abundantly supplied, and yet they remained unsatisfied and querulous. It is therefore said, that they demanded meat lnphsm, for their souls; i e., not for their real wants, which they might rationally and lawfully desire to have supplied, but to gratify their sensitive and carnal appetites. Our English Bible, and Calvin on the margin of the French version, give a very happy translation, They tempted God, by asking meat for their lust

And they tempted God in their heart - Exodus 16:2. The heart was the source of the evil. They were not satisfied with what he gave them. They asked for that which would be more agreeable to them, and they did it with a complaining and a murmuring spirit. It is not wrong in itself to ask of God that which will be better than what we now possess, for that is the object of all our prayers; but this may be done from a wrong motive - for mere self-gratification, as was the case here; or it may be with a complaining and dissatisfied spirit, such as was evinced on this occasion. In such a case we cannot expect the prayer to be answered "except as a punishment."
By asking meat for their lust - Food. The word "meat" here does not necessarily denote animal food, as it does with us. They asked another kind of food than manna; and they did it, not because this was "necessary" to sustain life, but in order to gratify their appetites. The original word here, however, is not "lusts," but "souls;" that is, "they asked food for themselves."

By asking meat for their lust - לנפשם lenaphsham, "for their souls," i.e., for their lives; for they said in their hearts that the light bread, the manna, was not sufficient to sustain their natural force, and preserve their lives. It seems, however, from the expression, that they were wholly carnal; that they had no spirituality of mind; they were earthly, animal, and devilish.

And they tempted God in their heart by (l) asking meat for their lust.
(l) Then to require more than is necessary, and to separate God's power from his will, is to tempt God.

And they tempted God in their heart,.... Which is desperately wicked, and from whence all impiety flows; they entertained hard thoughts of God; they inwardly fretted at their present circumstances, and secretly repined and murmured against God, and wished for things they should not; not being contented with what they had, and thankful for them, as they ought to have been:
by asking meat for their lust; or, "for their soul"; such as their souls lusted after, and their sensitive appetites craved; for they were not satisfied with the bread they had, which was sufficient for their sustenance and support; they wanted food for pleasure and wantonness; to ask for daily bread is right, but to ask for more to consume on our lusts is wrong, James 4:3.

in their heart-- (Matthew 15:19).
for their lust--literally, "soul," or, "desire."
provoking--and--tempted--illustrated by their absurd doubts,

Tempted - Desired a proof of God's power. Lust - Not for their necessary subsistence, but out of an inordinate and luxurious appetite.