Mishneh Torah — Positive Mitzvot מצוות עשה, Chapter 75
The full Hebrew text of Mishneh Torah, Positive Mitzvot, Chapter 75, with English translation by Maimonides (Rambam).
להקריב הזבה קרבן אחר שתטהר, שנאמר: "ואם טהרה, מזובה" (ויקרא טו,כח).
For a zavah to offer a sacrifice when she be-comes purified [after her affliction], as [Leviticus 15:28] states: "When she becomes pure from [the condition] of zavah...."