Abdur Rahman bin al-Qasim (may Allah have mercy on him) reports from his father (may Allah have mercy on him) that a Muslim woman began to have istihadah (irregular bleeding), and she asked the Messenger of Allah (peace and blessings be upon him) (and he mentioned the rest of the hadith).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحيض / 1656