Is the pardon for slight impurity based on a religious text or tradition, or is it merely a jurisprudential interpretation?

Forgiveness for a small amount of impurity (najasah) is not all-encompassing for all impurities; rather, it is specific to some and not others, such as a small amount of blood and what is related to it like pus and serous discharge. The majority of scholars based this on the Prophet’s (peace be upon him) silence regarding the command to wash off a small amount of menstrual blood, the actions of the Companions, and the Sharia’s removal of hardship. Ibn Qudamah elaborated on this in Al-Mughni, clarifying that it is difficult to guard against a small amount of blood, and that most scholars hold the view that it is overlooked. He cited the action of Aisha (may Allah be pleased with her) in dealing with a small amount of menstrual blood, and that this would not have been hidden from the Prophet (peace be upon him), as well as the saying of the Companions, which indicates a consensus.