Musannaf Ibn Abi Shaybah 19495 — Those who said her waiting period

Sayyiduna Ibn Umar (may Allah be pleased with them both) used to say: She observes a waiting period of three menstrual cycles, until Sayyiduna Uthman (may Allah be pleased with him) said this; then he used to give rulings according to it, and he would say: He was the best of us and the most knowledgeable of us.