Muhammad ibn Al-Rabi' Al-Aqra', from Sifah ibn Amirah, from Mansur ibn Hazim, from Ibn Abi Ya'fur: Abu Abdillah عليه السلام said: "A woman in a state of istihadah (prolonged irregular bleeding) should, after the days of her usual menstrual cycle have passed, perform ghusl (ritual purification), insert a piece of cotton (kursuf) to absorb the blood, and then observe. If the blood appears on the cotton, she should add another piece of cotton, perform wudu' (ablution), and then pray."