Sayyiduna Anas bin Malik (may Allah be pleased with him) states that the menstruation of a menstruating woman is five, six, seven, eight or ten days; then she is to take a ritual bath, fast and pray.
This hadith is known through al-Jald bin Ayyub, and it has been objected to as coming from him.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحيض / 1544