Musnad Ahmad 25:1397

Muhammad ibn Bakr narrated to us, Ibn Jurayj informed us, he said: Al-Hasan ibn Muslim informed me, from Tawus, he said: I was with Ibn Abbas when Zayd ibn Thabit said to him: "Do you issue a fatwa that the menstruating woman may depart before her last act is at the House (the Kaaba)?" He said: "Yes." He said: "Then do not issue a fatwa for that." Ibn Abbas said to him: "If you insist, then ask such-and-such Ansari woman, did the Prophet, peace and blessings of Allah be upon him, command her with that?" Zayd ibn Thabit returned to him laughing, and saying: "I do not see you as anything but having spoken the truth."