Al-Hasan (may Allah have mercy on him) said that the Messenger of Allah (peace and blessings be upon him) forbade that a slave woman be married in addition to a free wife.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 14001
Al-Hasan (may Allah have mercy on him) said that the Messenger of Allah (peace and blessings be upon him) forbade that a slave woman be married in addition to a free wife.
This is mursal (a report missing the Companion in its chain), except that it is in line with the meaning of the Book (of Allah), and with it is the view of a group of the Companions (may Allah be pleased with them).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 14002
Zirr bin Hubaysh narrates from Sayyiduna Ali (may Allah be pleased with him) that when a free woman is married while (the man already has) a slave wife, he should allot two days of the turn to her and one day to the slave woman; and it is not appropriate for a slave woman to be married while there is a free wife.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 14003
Sayyiduna Jabir bin Abdullah (may Allah be pleased with them both) said that a slave woman should not be married in addition to a free wife, while a free woman may be married in addition to a slave wife; and whoever is able to pay the dowry of a free woman should never marry a slave woman.
This chain is sahih (authentic).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 14004
Imam Malik (may Allah have mercy on him) was informed that Sayyiduna Abdullah bin Abbas and Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) were asked about a man who had a free woman as his wife and wished to marry a slave woman in addition to her; they both disliked that he should combine the two.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 14005
Ash'ath (may Allah have mercy on him) narrates from al-Hasan (may Allah have mercy on him) that he said regarding a man who married a free woman and a slave woman in a single contract: "He and the slave woman are to be separated."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 14006