וְהֶעָנָ֗ן סָ֚ר מֵעַ֣ל הָאֹ֔הֶל וְהִנֵּ֥ה מִרְיָ֖ם מְצֹרַ֣עַת כַּשָּׁ֑לֶג וַיִּ֧פֶן אַהֲרֹ֛ן אֶל־מִרְיָ֖ם וְהִנֵּ֥ה מְצֹרָֽעַת׃
Ketika awan itu beranjak dari atas kemah, tampaklah Miryam kena kusta seperti salju. Harun berpaling kepada Miryam, dan tampaklah ia kena kusta.
Rashi
והענן סר AND THE CLOUD DEPARTED, and only afterwards, ומרים מצרעת כשלג BEHOLD, MIRIAM BECAME LEPROUS, WHITE AS SNOW. A parable! This may be compared to a king who said to his son’s tutor, “Chastise my son, but do not do so until I go away from you, because I feel pity for him” (Sifrei Bamidbar 105).
Sforno
והענן סר, as one needs to keep one’s distance from anyone afflicted with tzoraat, and so that the afflicted person could be removed from the encampment of the people.
Or HaChaim
והנה מצרעת, and here she was afflicted with Tzoraat. There was no need to repeat this seeing the Torah had already mentioned it in the first half of our verse. According to Sifri who claims that Aaron too had been afflicted the repetition could mean that whereas Aaron had already been cured Miriam continued to be afflicted. According to Sifri Aaron's affliction disappeared as soon as he turned towards Miriam. Accordingly, we would have to assume that Moses had not been looking at Miriam at all. Why else would he have to be informed by Aaron of her affliction before he would pray for her?