ויקרא ט״ו:י״ט-כ״ד

כי תהיה זבה. יָכוֹל מֵאֶחָד מִכָּל אֵבָרֶיהָ, תַּ"ל וְהִיא גִּלְּתָה אֶת מְקוֹר דָּמֶיהָ — אֵין דָּם מְטַמֵּא אֶלָּא הַבָּא מִן הַמָּקוֹר:

כי תהיה זבה AND IF A WOMAN HAVE AN ISSUE — One might think that this means: if there be an, issue from any limb of her body (e. g. ear, nose)! It, however, states in a law referring to this matter, (Leviticus 20:18) “and she hath uncovered the fountain of her blood” — only that issue of blood therefore makes her unclean which comes from her fountain (Sifra, Metzora Parashat Zavim, Section 4 2).

דם יהיה זבה בבשרה. אֵין זוֹבָהּ קָרוּי זוֹב לְטַמֵּא אֶלָּא אִם כֵּן הוּא אָדֹם (שם י"ט):

דם יהיה זובה בבשרה AND HER ISSUE IN HER FLESH BE BLOOD — Her issue does not come under the term “flux” to cause uncleanness except if it is red (cf. Niddah 19a).

בנדתה. כְּמוֹ וּמִתֵּבֵל יְנִדֻּהוּ (איוב י"ח) — שֶׁהִיא מְנֻדָּה מִמַּגַּע כָּל אָדָם:

בנדתה [SHE SHALL BE] PUT APART [SEVEN DAYS] — The word has the same meaning as, (Job. 18:18) “and they shall drive him out (ינדהו) of the world” — and her state is so called because she is set apart from the touch of any person (separated, so that no-one shall touch her).

תהיה בנדתה. אֲפִלּוּ לֹא רָאֲתָה אֶלָּא רְאִיָּה רִאשׁוֹנָה (ספרא):

תהיה בנדתה [SEVEN DAYS] SHALL SHE BE IN HER SEPARATION. even though she has seen a show of blood only once (lit., only the first show — i. e., not 7 days continuously) (Sifra, Metzora Parashat Zavim, Section 4 5).

ואם על המשכב הוא. הַשּׁוֹכֵב אוֹ הַיּוֹשֵׁב עַל מִשְׁכָּבָהּ אוֹ עַל מוֹשָׁבָהּ אֲפִלּוּ לֹא נָגַע בָּהּ, אַף הוּא בְּדַת טֻמְאָה הָאֲמוּרָה בַּמִקְרָא הָעֶלְיוֹן, שֶׁטָּעוּן כִּבּוּס בְּגָדִים:

ואם על המשכב הוא AND IF ONE BE ON HER PLACE OF REPOSE [OR ON ANY THING WHEREON SHE SITTETH] — This means, one who sleeps or sits on the place where she has slept or has sat even though he does not directly touch it (e. g. if there are covers upon the couch or the seat; for if he touches it vv. 21 and 22 apply); he also comes under the law of uncleanness that is stated in the above verse — that he requires washing of garments.

על הכלי. לְרַבּוֹת אֶת הַמֶּרְכָּב:

על הכלי UPON A VESSEL — This is intended to add to משכב and מושב any article for riding on (Sifra, Metzora Parashat Zavim, Section 4 15).

בנגעו בו. אֵינוֹ מְדַבֵּר אֶלָּא עַל הַמֶּרְכָּב שֶׁנִּתְרַבָּה מֵ"עַל הַכְּלִי":

בנגעו בו WHEN HE TOUCHETH IT — "it" (בו) — this refers only to מרכב which, as has just been stated, is included in the law on account of the words על הכלי.

בנגעו בו יטמא. וְאֵינוֹ טָעוּן כִּבּוּס בְּגָדִים, שֶׁהַמֶּרְכָּב אֵין מַגָּעוֹ מְטַמֵּא אָדָם לְטַמֵּא בְגָדִים (כלים פכ"ג):

בנגעו בו יטמא WHEN HE TOUCHETH IT HE SHALL BE UNCLEAN, but does not require washing of the garments, because so far as the מרכב is concerned its being touched does not communicate uncleanness to people so that they in turn should render their garments unclean (cf. Mishnah Kelim 23:3).

ותהי נדתה עליו. יָכוֹל יַעֲלֶה לְרַגְלָהּ — שֶׁאִם בָּא עָלֶיהָ בַחֲמִישִׁי לְנִדָּתָהּ לֹא יִטְמָא אֶלָּא שְׁלוֹשָׁה יָמִים כְּמוֹתָהּ — תַּ"ל וְטָמֵא שִׁבְעַת יָמִים, וּמַה תַּ"ל וּתְהִי נִדָּתָהּ עָלָיו? מַה הִיא מְטַמְּאָה אָדָם וּכְלֵי חֶרֶס, אַף הוּא מְטַמֵּא אָדָם וּכְלֵי חֶרֶס (ספרא; נדה ל"ג):

ותהי נדתה עליו [AND IF ANY MAN LIE WITH HER AT ALL] THEN SHALL HER UNCLEANLINESS OF SEPARATION BE UPON HIM — One might think that he follows in her wake — that if he had intercourse with her e. g. on the fifth day of her separation he shall become unclean for three days only (for the fifth, sixth and seventh) like herself (i. e. because these are the remaining days during which she is unclean)! Scripture, however, states: "he shall be unclean seven days”. Therefore these words cannot refer to the duration of her uncleanness. What then is the force of ותהי נדתה עליו? They mean: her state of uncleanness as a נדה shall be upon him. How is it in the case of her? She, being an אב הטומאה, makes man unclean, and also earthen vessels by means of ‎‎היסט! So, too, he becomes an אב הטומאה (not a ולד הטומאה), and makes man unclean, and also earthen vessels by means‎ of היסט! (Niddah 33a)