Num 20:1

“Next comes "And the Lord shall shake the desert of Kadesh." This still refers to the spirit of piety. The account in Numbers carefully explains this reference when it tells how the people of Israel came to Kadesh and were suffering from excessive thirst because of the aridity of that place. Moses struck a rock at the Lord's command and suddenly provided an abundance of water for them. In a remarkable way the earth, which lay foul with unwatered dustiness, was irrigated. By this comparison the prophet says that the most obdurate hearts of sinners can be liquefied into waters of wisdom. The example of Kadesh must be reenacted in human hearts. The term desert is often used of places where unfaithful people are known to gather, as the Gospel says: "The voice of one crying in the desert." John could not have preached in the desert where none could hear. Rather, "desert" is used to describe those who had not as yet apprehended the gifts of faith.”