Kedushat Levi on Mei Merivah

(4) ‎Numbers 20,8. “you are to speak to the rock in full view of ‎them, etc.”, “because you did not have enough faith in Me to ‎sanctify Me in full view of the Israelites.” ‎
Rashi and Nachmanides disagree with one another ‎concerning what was Moses’ sin. One says the sin was that he ‎addressed the Israelites by calling them “obstinate, rebellious” ‎people, i.e. ‎שמעו נא המורים‎, whereas the other sage claims that ‎Moses’ sin consisted in striking the rock instead of speaking to it.‎

I believe that Rashi and Nachmanides do not really ‎disagree because the cause that Moses was angry enough to strike ‎the rock was the rebelliousness of the people.‎
Rebuking people, especially the Jewish people, calling them to ‎order, can be done by two different methods. Both methods are ‎designed to make the people carry out the will of the Creator.

‎One approach stresses the greatness of the Lord, and presents ‎this as the reason why not obeying His commands is a non ‎starter. It reminds the people that their very souls originate ‎immediately beneath the Creator’s throne in heaven(an expression that means very high place-N.C.) . It reminds ‎people of their duty to provide G’d with the pleasure of observing ‎His people performing His will. When the people listen to this ‎kind of rebuke their hearts will surely be moved in the right ‎direction and they will realize that it is incumbent upon them to ‎accept the yoke of heaven.‎

The other method of admonishing people stresses reminding ‎people of the results of their failure to respond to the rebukes, ‎the penalties in store for them. It is customary that when using ‎this latter dimension of mussar, commonly known as ‎the “fire and brimstone” approach, the preacher relies on the ‎feelings of shame in every individual causing him to turn away ‎from doing evil and do good instead.‎
The difference between these two methods is that the first ‎method relies on reminding the subject of his high rank among ‎the creatures G’d has created, a fact that makes it their duty not ‎to go astray. giving

This former method, through constantly pointing ‎out Israel’s great virtues etc., will likely evoke in the listener a ‎desire to conduct himself in a way that will justify the ‎compliments paid to him by the person doing the rebuking.

The ‎person using the method of harping on the wrongs the people ‎are guilty of all the time, cannot at the same time arouse the ‎feeling that they are basically highly valued people in G’d’s eyes, ‎and need only to correct a flaw that has been brought to their ‎attention on this occasion. The person who rebukes the sinner on ‎this occasion, by acknowledging that though accused of an error, ‎whether committed through negligence or even knowingly, he is ‎still considered as part of G’d’s people, i.e. part of the elite of the ‎human species, will evoke reciprocal feelings in those whom he ‎addresses.

Moses, on this occasion, chose to use the method of ‎belittling the people and to shame them. It was therefore in ‎keeping with this approach that he struck the rock, symbolizing ‎how an obstinate rock has to be treated. ‎
‎[I believe that the author assumes that one of the ‎rocks Moses faced was the one which had before Miriam’s death, ‎reported earlier, always supplied the Israelites with water. If this ‎were not so the symbolism is lost on me, as stones bringing forth ‎water were unheard of. Ed.]‎
Since G’d a) had not instructed Moses to berate the people for ‎demanding water, and b) would have preferred for him to choose ‎the first method of rebuking, He had thereby missed an ‎opportunity to demonstrate that even words sounding like ‎compliments addressed to an erring Israelite when criticizing a ‎sin, or even all of them at the right time, in the right ‎circumstances, would have the desired effect on people of the ‎spiritual greatness of Israel.

This is all alluded to in G’d’s telling ‎Moses about his failure to have grasped the opportunity to ‎sanctify His Name before all the Israelites.‎