2,113. External Sources of Stains
Hilchos Issurei Biah 9:19
Let’s say that there’s a stain that would cause a woman to be rendered unclean but there’s some external thing to which the stain might be attributed. If the stain is found on a garment, the woman is clean because the Sages said that one should rule leniently in such situations. If the stain is found on her skin, she is deemed unclean out of doubt and may not attribute the stain to the other cause. If there’s more reason to attribute a stain on her skin to another cause than there is to attribute one on her clothing, then she may attribute even one on her skin to that cause. In such a case, the woman is clean despite any doubt.
Hilchos Issurei Biah 9:20
Pursuant to the previous halacha, if a woman slaughtered an animal or bird, occupied herself with stains, sat next to people who were occupied with stains, or passed through a butcher’s market, then if blood was found on her outer garment, she is pure. The woman is permitted to attribute the stain to these causes because of the likelihood that it came from them.