Hadith: Ghaylān ibn Salamah Ath-Thaqafi embraced Islam and he had ten wives from the pre-Islamic period of ignorance, and they all embraced Islam with him. The Prophet (may Allah's peace and blessings be upon him) commanded him to choose four of them

عن ابن عمر، أن غَيْلَانَ بن سَلَمَةَ الثقفي أَسْلَمَ وله عشر نِسْوَةٍ في الجاهلية، فَأَسْلَمْنَ معه، « فَأَمَرَهُ النبي صلى الله عليه وسلم أن يَتَخَيَّرَ أربعا مِنْهُنَّ».
[صحيح] - [رواه الترمذي وابن ماجه وأحمد]

Ibn ‘Umar (may Allah be pleased with him) reported: Ghaylān ibn Salamah Ath-Thaqafi embraced Islam and he had ten wives from the pre-Islamic period of ignorance, and they all embraced Islam with him. The Prophet (may Allah's peace and blessings be upon him) commanded him to choose four of them.
[Authentic hadith] - [Narrated by Ibn Majah - Narrated by At-Termedhy - Narrated by Ahmad]

Explanation

This Hadīth shows one of the different forms of marriage that existed before Islam. Men would combine a big number of women in marriage without restriction. Ghaylān, a Companion, embraced Islam while he had ten wives, who also embraced Islam with him. The Prophet (may Allah's peace and blessings be upon him) commanded him to choose four of them and part with the rest. In Islam, a man may have four wives, and there is a consensus among Muslims on that.