Sulayman bin Yasar (may Allah have mercy on him) narrates that Ibn Marjanah (may Allah have mercy on him) narrated to him from Sayyidah Umm Salamah (may Allah be pleased with her) that in the time of the Prophet (peace and blessings be upon him) there was a woman whose blood would flow (continuously). So Sayyidah Umm Salamah (may Allah be pleased with her) asked the Prophet (peace and blessings be upon him) about her, and the Prophet (peace and blessings be upon him) said: "Let her look at the number of days and nights in which she used to menstruate before this bleeding started, and their portion of the month (let her consider), and let her leave the prayer for that length of time. Then when she has passed beyond that, let her take a ritual bath, then bind herself with a cloth and pray."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19953