Musannaf Ibn Abi Shaybah 17451 — Those who said: istibra of a slave

Makhul said: I said to al-Zuhri: Do you not know that Sayyiduna Umar, until his term ended, and Sayyiduna Ibn Mas'ud in Iraq, until his term ended, and Sayyiduna Uthman bin Affan (may Allah be pleased with them) used to hold that a slave woman's freedom from pregnancy is established by one menstruation, whereas Sayyiduna Mu'awiyah (may Allah be pleased with him) held that one should wait for two menstruations.