Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: A concession has been granted to the menstruating woman to go back once she has performed the ifadah. Abu Amr (may Allah have mercy on him) added in his narration that he (Tawus) said: At first I heard Sayyiduna Ibn Umar (may Allah be pleased with them both) say that she may not go back; then I heard him say: "The Messenger of Allah (peace and blessings be upon him) granted them a concession."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9758