John Calvin Commentary Psalms 106:15

"And he gave them their request, But sent leanness into their soul." — Psalms 106:15 (ASV)

He gave them their desire. There is a fine play on words involving the Hebrew word רזון, razon, for if, instead of ז, zain, we read ץ, tsädhé, the word would signify good pleasure. The prophet, therefore, alluding to their lusting, by a word very similar to "good pleasure" or "desire," says that God sent leanness into their souls; meaning by this that God had indeed gratified the people's inordinate desires, but in such a way that those who had loathed the manna now received nothing but leanness.

Thus, the prophet seems to charge the people with a condition we daily observe among those who live luxuriously and are fastidious, especially when their stomach, impaired by what they have consumed, has no appetite for wholesome food. For such persons only enjoy food that is harmful; consequently, the more they indulge themselves with it, the more they become entrenched in damaging habits, and so, in a very short time, this very food causes them to waste away.

The prophet, therefore, seems to apply to the mind what he says about the unhealthy state of the body, comparing the Jews to those unhealthy individuals whose ravenous appetite, instead of promoting health, injures it, because they do not derive any nourishment from their food. The reason for this is that God withheld His blessing from the food they had so excessively craved, so that this punishment for their transgression might humble them.

But their perversity is shown to be very great, because even this method of punishing them did not overcome their stubborn hearts. It is a proverbial saying that fools learn wisdom from experiencing hardship. How senseless and incorrigible they must have been, whom even compulsion itself could not reform!