Sayyiduna Ibn Umar (may Allah be pleased with them both) related that a man from Thaqif called Ghaylan bin Salamah accepted Islam while he had ten wives, so the Messenger of Allah (peace and blessings be upon him) ordered him to choose four of them and leave six.
Hadith Referenceالمعجم الكبير للطبراني / باب الغين / 15749