Musar for Numbers 21:9

ויעש משה נחש נחושת . The Tzror Hamor, in his commentary on Parshat Bo, in connection with the מזוזות ומשקוף, describes how jealous G–d was of the honor of the righteous, more so even than of His own honor. This is why the word מזוזות, plural, is mentioned first (corresponding to Moses and Aaron), whereas the word משקוף, lintel (which is above the מזוזות which corresponds to G–d), is mentioned last. Moses was unwilling to have that which symbolized G–d mentioned last, therefore when relaying the command, he mentioned the word משקוף first (compare Exodus 12,7, when G–d commands Moses, and Exodus 12,22, where Moses relays these instructions to Israel). We have a similar situation here in chapter 21,5-9. The people spoke up against G–d and against Moses. G–d dispatched נחשים ושרפים against them, the נחשים because they had spoken out against G–d, the שרפים because of their having criticized Moses who is compared to an angel of the שרף variety. Therefore, after the people repented, G–d told Moses to make a שרף for himself to put it on a pole, etc. Moses however, did not make a שרף; he rather made a נחש, seeing that he considered restoring G–d's honor as more important than restoring his own honor, even though a שרף was what G–d had instructed him to make. From all this we learn to what extent we must be careful not to besmirch the honor of Torah scholars, righteous people, etc.