Umm Bakrah al-Aslamiyyah (may Allah be pleased with her) took khul' from her husband Abdullah bin Usayd (may Allah be pleased with him). Then they came to Uthman (may Allah be pleased with him), and he said: "It is one divorce, unless you named something, in which case it is what you named."
A musnad (connected) hadith has been narrated on this, but its chain is not established. It has also been narrated from Ali and Ibn Mas'ud (may Allah be pleased with them both). Ibn al-Mundhir said: Ahmad bin Hanbal declared the report of Uthman weak, and the chains of the reports of Ali and Ibn Mas'ud (may Allah be pleased with them both) have been criticised; there is nothing in this chapter more sound than the report of Ibn Abbas, meaning the report of Tawus from Ibn Abbas (may Allah be pleased with them both).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الخلع والطلاق / 14864