Leviticus 15:18-20

New Revised Standard Version, Anglicised Catholic Edition

¹⁸ If a man lies with a woman and has an emission of semen, both of them shall bathe in water, and be unclean until the evening.

¹⁹ When a woman has a discharge of blood that is her regular discharge from her body, she shall be in her impurity for seven days, and whoever touches her shall be unclean until the evening. ²⁰ Everything upon which she lies during her impurity shall be unclean; everything also upon which she sits shall be unclean.