Narrated from Amr ibn Uthman, from Al-Hasan ibn Mahbub, from Ali ibn Ri'ab, from Malik ibn A'yan: I asked Abu Ja'far عليه السلام about a woman in a state of istihadah (prolonged irregular bleeding) and how her husband may approach her. Imam عليه السلام said: "He should observe the days during which she used to menstruate when her cycle was regular, and he should not approach her during those days of the month. However, he may approach her during the other days. But he should not approach her until he instructs her to perform ghusl (ritual purification), and then he may approach her if he so desires."