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.”
Source: The Enarrations, or Expositions, on the Psalms (New Advent)