Vaishnava Dharmashastra 22.91

22.91

mṛttoyaiḥ śudhyate śodhyaṃ nadī vegena śudhyati
rajasā strī manoduṣṭā saṃnyāsena dvijottamāḥ //

By water and earth is purified what should be purified (because it has been defiled); a river is purified by its current (carrying away all slime and mud); a woman, whose thoughts have been impure, by her menses,; and the chief among the twice-born (the Brâhmanas), by renouncing the world.