Musar к Бамидбар 20:13

And (Sanhedrin 101a): "R. Chisda said: 'If one argues against his Rabbi, it is as if he would argue against the Shechinah, viz. (Numbers 26:9) ["who strove against Moses and Aaron with the congregation of Korach] when they strove against the L-rd."' And R. Chamma b. Chanina said: "If one quarrels with his Rabbi it is as if he would quarrel with the Shechinah, viz. (Numbers 20:13): "They are the waters of Merivah (contention), whereby the children of Israel strove with the L-rd" [in striving with Moses].'" And, along the same lines: "R. Chaina b. Pappa said: 'If one rails against his Rabbi, it is as if he would rail against the Shechinah, etc.' … R. Avihu said: 'If one arraigns his Rabbi, it is as if he would arraign the Shechinah, etc.'" And the four levels that the Gemara mentions below are meant to apprise us that even thinking alone [against one's Rabbi] is also a great issur.

In view of this we can also understand Deut. 1,37, when Moses said: "G–d was also angry with me on your account." Moses employs the expression בי, against me. We find the same expression here when G–d said to him יען כי לא האמנתם בי להקדישני, "because you did not have enough faith in Me to sanctify Me" (20,12). In Deut. 1,32, however, the wording is ובדבר הזה אינכם מאמינים. The true significance is as I have explained, that a decree already existed, but the actions needed to trigger this decree had not yet occurred. Because of a previous sin Moses had committed, G–d had already become angry at Moses on account of Israel. Now this anger, i.e. decree, became translated into effective reality. This is the reason why the Torah stresses המה מי מריבה אשר רבו בני ישראל, "these are the very same waters of strife the children of Israel quarreled (already previously)." If it were not so, the expression המה, would be uncalled for. Now the various commentaries that have been offered on this passage.