Should a woman who has post-partum bleeding wait for forty days without fasting or praying, or is the criterion for this the cessation of blood, and that whenever it is that she attains purity, she should perform Ghusl and pray? What is the minimum period of post-partum bleeding?
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Shaykh Ibn ‘Uthaymeen said: "There is no specific period of time for post partum bleeding. As long as there is blood the woman should not pray nor fast and her husband should not have intercourse with her. If a woman attains purity from this, even if before the completion of the forty days, such as after five or ten days, then she should pray and fast and her husband can have sexual intercourse with her. This is because post-partum bleeding is something tangible and its rulings depend on its existence or absence. Thus, when there is blood, the rulings of post-partum bleeding apply and when there is no blood, all the rulings cease to apply. However, if the blood lasts for more than sixty days, it would then be considered vaginal bleeding and not post-partum bleeding, and she should abandon the prayer only for the usual number of days of menstruation after the maximum sixty days, then perform Ghusl and pray."
Allaah Knows best.