פּירוש אויף שמות 2:13

שני אנשים עברים TWO MEN OF THE HEBREWS — viz., Dathan and Abiram (Nedarim 64b); it was they, too, who left over some of the manna (Exodus Rabbah 1:29).

And he said to the wicked one, “Why do you strike your fellow?” Rashi explained that even though he did not strike him by raising his hand, he is called wicked; “your fellow” — a wicked one like yourself. But this is difficult: Who told Moses that this one was wicked like the other? Furthermore, where is it written that he sought to strike him, as it does not say “and he raised his hand to strike him”?
It seems to me that the language of striking [hakkah] also applies to speech, as it is written: There is one who speaks rashly like the piercings of a sword (Proverbs 12:18). And it is written: Cursed be he who strikes his fellow in secret (Deuteronomy 27:24). For one who casts a blemish upon his fellow, there is no greater strike than this. And our Sages of blessed memory said (Kiddushin 70a), “Whoever invalidates others, does so with his own blemish.”
Moses saw two Hebrews fighting with insults and blasphemies, and therefore both of them were wicked, for it is the trait of the righteous to be among those who are insulted but do not insult, who hear the voice of those who revile them but do not respond. He called him “your fellow, a wicked one exactly like yourself,” because with the same blemish that you invalidate him and strike him with the whip of your tongue, surely that same blemish is found in you as well, for whoever invalidates others does so with his own blemish. Therefore he said: Why do you strike your fellow?, because he is your fellow in this blemish.

ויאמר לרשע, seeing that each one of them was one of his brethren he did not act as avenger but intervened with words rebuking the aggressor.

נצים means quarelling.

למה תכה lit., WHEREFORE WILT THOU SMITE — Although he had not yet smitten him he is termed here רשע wicked, because he had merely raised his hand against him (Sanhedrin 58b).