Sayyidah Aishah (may Allah be pleased with her) said: "The Messenger of Allah (peace and blessings be upon him) did not favour any of us over another in dividing his turns, and there was hardly a day on which he (peace and blessings be upon him) did not go round to all of us and come close to each woman among us, without intimacy, until he reached the one whose day it was, and he would spend the night with her. And Sawdah bint Zam'ah, who had reached old age, when he (peace and blessings be upon him) intended to part from her, said: My day with you and my share are for Aishah, and he (peace and blessings be upon him) accepted that from her." So it was concerning her that this verse was revealed: "And if a woman fears ill-conduct or turning away from her husband, there is no sin on them both if they make a settlement between themselves." [Surah al-Nisa: 128]
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20452