Muwatta Imam Malik Book of Divorce, Hadith 76

Yahya related to me from Malik that Ibn Shihab said, "I have heard that the Messenger of Allah ﷺ said to a man from Thaqif who had ten wives when he became muslim, 'Take four and separate from the rest.' "

وَحَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنِ ابْنِ شِهَابٍ، أَنَّهُ قَالَ بَلَغَنِي أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ لِرَجُلٍ مِنْ ثَقِيفٍ أَسْلَمَ وَعِنْدَهُ عَشْرُ نِسْوَةٍ حِينَ أَسْلَمَ الثَّقَفِيُّ " أَمْسِكْ مِنْهُنَّ أَرْبَعًا وَفَارِقْ سَائِرَهُنَّ " .