Kommentar zu Wajikra 15:29

והביאה אותם אל הכהן, “and she will bring them (the two birds) to the priest;” whence do I know that this woman is permitted to immerse herself in a ritual bath before the evening, even? The clue are the words: ”to the entrance of the Tent of Meeting;” how could she have done this on this day if she had not first immersed herself in a ritual bath? She would still have been ritually impure? Having immersed herself in a ritual bath before sunset enabled her to bring the birds to the priest still on the same day. (Sifra)