Midrash su Levitico 15:13

1) (Vayikra 15:13) ("And when the zav is cleansed of his flux, then he shall count for himself seven days for his cleansing, and he shall wash his clothes and bathe his flesh in running water, and he shall be clean.") "and when the zav is cleansed of his flux": when his flux ceases. "of his flux": of his flux and not of his plague-spot (If in addition to his flux he had a [leprous] plague-spot, he need not wait until he is also healed of his plague-spot, but he may count the seven days for it immediately and be cleansed thereby from the specific tumah conferred by a zav.) "of his flux and he shall count": Even a partial flux (i.e., fewer than three) requires the seven-day count.

2) to include one who has two zav sightings as requiring the seven-day count. (Why do we need a verse for this?) Does it not follow (of itself)? If he confers mishkav and moshav tumah with two sightings, should he not require the seven-day count with two sightings? (No, this is refuted by zavah, who confers mishkav and moshav tumah with two sightings, but does not count (seven days) for two sightings (See below, Chapter 8:6).

3) Do not wonder then about a zav, even though he confers mishkav and moshav tumah with two sightings, if he would not require the seven-day count with two sightings. It must, therefore, be written "of his flux and he shall count." Even a partial flux requires the seven-day count, to include one who has two sightings as requiring the seven-day count.