12 And yet, “they,” like a generation crooked and embittering, “added yet to sin against Him”: that is, not to believe. For this is the sin, whereof the Spirit does convict the world, as the Lord says, “Of sin indeed because they have not believed on Me.” “And they exasperated the Most High in drought,” which other copies have, “in a place without water,” which is a more exact translation from the Greek, and does signify no other thing than drought. Was it in that drought of the desert, or rather in their own? For although they had drank of the rock, they had not their bellies but their minds dry, freshening with no fruitfulness of righteousness. In that drought they ought the more faithfully to have been suppliant unto God, in order that He who had given fullness unto their jaws, might give also equity to their manners. For unto him the faithful soul does cry, “Let my eyes see equity.”
13. “And they tempted God in their hearts, in order that they might seek morsels for their souls”. It is one thing to ask in believing, another thing in tempting. Lastly there follows, “And they slandered God, and said, Shall God be able to prepare a table in the desert?”. “For He smote the rock, and the waters flowed, and torrents gushed forth: will He be able to give bread also, or to prepare a table for His people?”. Not believing therefore, they sought morsels for their souls. Not so the Apostle James does enjoin a morsel to be asked for the mind, but does admonish that it be sought by believers, not by such as tempt and slander God. “But if any one of you,” he says, “does lack wisdom, let him ask of God, who does give to all men abundantly, and does not upbraid, and it shall be given to him: but let him ask in faith, nothing wavering.” This faith had not that generation which “had not directed their heart, and the spirit thereof had not been trusted with God.”
14. “Wherefore the Lord heard, and He delayed, and fire was lighted in Jacob, and wrath went up into Israel”. He has explained what he has called fire. He has called anger fire: although in strict propriety fire did also burn up many men. What is therefore this that he says, “The Lord heard, and He delayed”? Did He delay to conduct them into the land of promise, whither they were being led: which might have been done in the space of a few days, but on account of sins they must needs be wasted in the desert, where also they were wasted during forty years? And if this be so, He did then delay the people, not those very persons who tempted and slandered God: for they all perished in the desert, and their children journeyed into the land of promise. Or did He delay punishment, in order that He might first satisfy unbelieving concupiscence, lest He might be supposed to be angry, because they were asking of Him what He was not able to do? “He heard,” then, “and He delayed to avenge:” and after He had done what they supposed He was not able to do, then “anger went up upon Israel.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)