“יען לא האמנתם בי להקדישני לעיני בני ישראל Because you did not believe in me to sanctify Me in the eyes of the children of Israel”
There are many explanations throughout the Rishonim explaining what sin Moshe committed in connection with the rock. The Ramban suggests that the sin was due to the fact that Moshe says “we will bring water from this rock” when Moshe should have said Hashem will bring water from this rock. Had Moshe said it in a language that attributed the miracle to Hashem, it would have brought the Jewish people to a higher level of faith in Hashem by making it clear that it was Hashem performing this miracle. The Sifsei Chaim points out that the Jewish people never believed that because Moshe said “we” will take water out of the rock that Moshe was performing this miracle. They understood that Hashem was performing the miracle and Moshe was just serving as an agent. Still, the slightest action that does not give full credit to Hashem is a lack of sanctification of Hashem’s name. Moshe Rabeinu, because of his position, was held to the highest standard of accountibility, and was punished for this error. With this in mind, we can understand what Hashem says to Moshe in Devarim 32:51 citing the reason he will not be able to go to Eretz Yisrael as because he performed Meila against Hashem. This Pasuk seems to be puzzling – Meila is when one benefits from something holy without permission. What does this have to do with the sin of Moshe? The answer is because Moshe took the slightest amount of credit and thereby took something that was Hashem’s and not his.
This is the constant test that we each have – to bring out the name of Hashem in everything we do, and to give Him proper credit. We need to be careful not to take the credit for ourselves. The Gemara tells us in Brachos 35b that one who benefits from this world without a Bracha is as if he too performed Meila because he is taking something without giving the proper credit to Hashem. We should always remember that everything in this world comes directly from Hashem and we should be sure to give Hashem the proper credit to insure that we bring honor and sanctification to his Name.