Niddah 1:6-7

Niddah 1:6

When they say that a woman’s time is sufficient, that refers to the first time one of the aforementioned four women sees blood. The second time, she conveys impurity retroactively for 24 hours. If she discovered the first flow because of an accident (such as jumping or carrying), then her time is sufficient even for the second.

Niddah 1:7

Even though they said that her time is sufficient, she must nevertheless perform a daily examination. Exclusions to this rule include a niddah and a woman experiencing pure blood following childbirth. A woman must also check herself using a cloth when she engages in marital intimacy, except for a woman experiencing pure blood following childbirth and a “virgin” (i.e., one who has not yet experienced menstrual bleeding), whose (hymeneal) blood is ritually clean. She must check herself twice a day – in the morning and at twilight – as well as when she is about to engage in intimacy. Women in kohein families must also check themselves before eating trumah. Rabbi Yehuda says they must also check themselves when they finish eating trumah.