Rashi on Leviticus 15:19/רש"י על ויקרא ט״ו:י״ט

1כי 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).

2דם 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).

3בנדתה [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).

4תהיה 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).