Qabisah bin Dhu'ayb (may Allah have mercy on him) said that a man asked Sayyiduna Uthman bin Affan (may Allah be pleased with him): May two sisters who are slave-women be combined? Sayyiduna Uthman (may Allah be pleased with him) said: One verse indicates that they are lawful and another verse that they are forbidden, but as for me, I dislike it. He (the narrator) said: The man left Sayyiduna Uthman (may Allah be pleased with him) and met a man from the Companions of the Prophet (peace and blessings be upon him), who said: If I had any authority, and then I found someone who had done this, I would make him an example for people. Imam Malik (may Allah have mercy on him) said that al-Zuhri (may Allah have mercy on him) said: I think he was Sayyiduna Ali bin Abi Talib (may Allah be pleased with him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 13930