Sulayman bin Yasar (may Allah have mercy on him) said that Nufay', who was the mukatab (a slave contracted to buy his freedom) or the slave of Umm Salamah (may Allah be pleased with her), had a free woman as his wife. He gave her two divorces, and then he wanted to take her back. The pure wives (of the Prophet) sent him to Uthman bin Affan (may Allah be pleased with him) so that he could ask him about it. He went to him and met him by the steps, where he was holding the hand of Zayd bin Thabit (may Allah be pleased with him). He asked them both, and both of them (may Allah be pleased with them both) hastened to answer: "She is forbidden to you, she is forbidden to you."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الخلع والطلاق / 15115