Sunan Ibn Majah, Chapter: The Chapters on Divorce

from Rubai bint Muawwidh bin Afra: He said: "I said to her: 'Tell me your Hadith.' She said: 'I got Khul' from my husband, then I came to Uthman and asked him: "What waiting period do I have to observe?" He said: "You do not have to observe any waiting period, unless you had intercourse with him recently, in which case you should stay with him until you have menstruated." In that he was following the ruling of the Messenger of Allah (saw) concerning Maryam Maghaliyyah, who was married to Thabit bin Qais and she got Khul from him.' "