Musannaf Ibn Abi Shaybah 19837 — An umm walad who is freed: how long

Yahya bin Abi Kathir (may Allah have mercy on him) said: Sayyiduna Amr bin al-As (may Allah be pleased with him) ordered an umm walad who had been set free to observe a waiting period of three menstrual periods, and he wrote this decision to Sayyiduna Umar (may Allah be pleased with him). Sayyiduna Umar (may Allah be pleased with him) approved of his opinion.