Nafi' (may Allah have mercy on him) narrates, with the chain of al-Layth (may Allah have mercy on him) and with the same meaning, that she should abandon the prayer for that length of time, then when the time of prayer comes she should take a ritual bath, bind herself with a cloth and pray.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحيض / 1580