וַיֹּ֨אמֶר יְהוָ֜ה אֶל־מֹשֶׁ֗ה וְאָבִ֙יהָ֙ יָרֹ֤ק יָרַק֙ בְּפָנֶ֔יהָ הֲלֹ֥א תִכָּלֵ֖ם שִׁבְעַ֣ת יָמִ֑ים תִּסָּגֵ֞ר שִׁבְעַ֤ת יָמִים֙ מִח֣וּץ לַֽמַּחֲנֶ֔ה וְאַחַ֖ר תֵּאָסֵֽף׃
永恆者對摩西說:「即使是她父親吐唾沫在她臉上,她豈不也要羞愧七天嗎?現在要把她關在營外七天,然後才可以讓她回到營中。」
Rashi
ואביה ירק ירק בפניה IF HER FATHER HAD BUT SPIT IN HER FACE — i.e. if he had shown her an angry face (if he was offended with her), הלא תכלם שבעת ימים SHOULD SHE NOT BE PUT TO SHAME FOR SEVEN DAYS? — It follows therefore à fortiori with respect to the Shechinah (i.e. in the case where God rebukes her in such a stern way) that she ought to be put to shame for fourteen days!) But since there is a rule דין לבא מן הדין להיות כנדון “It is sufficient for a law that is derived by a conclusion a fortiori (הבא מן הדין) to be only as strict as the law from which it is derived (נדון), and not go beyond it, therefore even as a consequence of My reprimand, תסגר שבעת ימים LET HER BE SHUT OUT [FROM THE CAMP] SEVEN DAYS only (Sifrei Bamidbar 106; Bava Kamma 25a).
Or HaChaim
ואביה ירוק ירק, "if HER father had spit in her face, etc." The Torah emphasises Miriam's experience as that of a daughter of G'd, i.e. a צדקת, rather than that of any father spitting at any daughter.