It is narrated from Sayyidah Hamnah bint Jahsh (may Allah be pleased with her) that she had prolonged bleeding (istihadah), and her husband used to have intercourse with her.
It is mentioned from Ibn Abbas that he permitted intercourse with her, and this is the view of Ibn al-Musayyib, al-Hasan, Ata, Sa'id bin Jubayr and others.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحيض / 1562