Sayyidah Asma' bint Umays (may Allah be pleased with her) said: I said: O Messenger of Allah! Fatimah bint Abi Hubaysh has had istihadah (irregular bleeding) since such-and-such a time, and she has not been able to pray. The Messenger of Allah (peace and blessings be upon him) said: "Subhan Allah! This is from Satan. Let her sit in a tub, and when she sees yellowness on top of the water, let her take one ritual bath for Zuhr and Asr, and one ritual bath for Maghrib and Isha, and perform ablution (wudu) in between."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20741