Tuhr literally means “purity” and refers to the ritual state of being free from hayd, nifas, and major ritual impurity (janabat). In the context of menstruation, tuhr is the time between cycles. The days a Shia woman prays, fasts, and worships normally.
The A. Sistani app shipped under the name Tuhr because tuhr. Not hayd. Is the goal of every classification call. The question is never “what bleeding category am I in?” by itself; it is “can I worship today?” The answer is one word: tuhr or not.
The ten-day rule
Per A. Sistani 492, at least ten days of tuhr must pass between two hayd cycles. Bleeding that begins sooner does not start a new hayd. It counts as istihada.
This is a load-bearing rule. If a Shia woman thinks her cycle started on day 8 of tuhr and stops praying, she has skipped prayers she was obligated to perform.
Tuhr restored: ghusl
After hayd ends, the woman performs ghusl al-hayd to formally re-enter tuhr. Until ghusl is completed, she remains in a state where prayer is not yet valid even though bleeding has stopped.
Tools
- Hayd vs istihada classifier. Applies the 10-day tuhr rule automatically.
Primary sources
- A. Sistani · 492 Ten clear days separate two distinct hayds
If a woman who usually experiences bleeding once a month experiences bleeding twice in one month, then in the event that the number of days on which her bleeding stops in between is not less than ten, she must consider both bleedings to be ḥayḍ even if one of them does not have the attributes of ḥayḍ.