Musannaf Ibn Abi Shayba 9:722

Abu Bakr narrated to us, from Abbad ibn al-Awwam, from Muhammad ibn Ishaq, from Makhul, who said: I said to al-Zuhri, "Do you not know that Umar, when his term ended, and Ibn Mas'ud in Iraq, when his term ended, and Uthman ibn Affan, they used to seek the purification of the slave woman with one menstrual cycle, until it was Mu'awiya, and he used to say two menstrual cycles?" Al-Zuhri said, "And I will add to you: Ubadah ibn al-Samit."