Purity: Bleeding Stopping Before Ten Days
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 494:
If a woman’s bleeding stops before ten days and she knows that there is no blood inside, she must perform ghusl for her ritual acts of worship even if she supposes that she will experience bleeding again before the completion of ten days. If she is certain that she will experience bleeding again before the completion of ten days, she must, as stated previously, perform ghusl as a precautionary measure, perform her ritual acts of worship, and refrain from doing the things that are unlawful for a ḥāʾiḍ.
-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)