Niddah 2:3-4

Niddah 2:3

“After a span of time” (in the previous mishna) means long enough for her to get out of bed and wash her face. After finding blood, she conveys ritual purity retroactively for 24 hours but not to the man with whom she was intimate; Rabbi Akiva says she also conveys impurity to the man. The Sages agree with Rabbi Akiva in a case where the woman sees a stain (on her clothes) that she also conveys impurity to the man with whom she was intimate.

Niddah 2:4

All women are presumed to be in a state of ritual purity vis-à-vis their husbands. If men return from a journey, their wives are presumed to be ritually clean. Beis Shammai say that a woman requires two examination cloths – one to be used before intimacy and one to be used after – or else she should examine the cloths by lamplight. Beis Hillel say that two cloths are sufficient for the whole night (regardless of the number of acts of intimacy).