Yahya related to me from Malik that Ibn Shihab said, "I have heard that the Messenger of Allah, may Allah bless him and grant him peace, 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 صلى الله عليه وسلم قَالَ لِرَجُلٍ مِنْ ثَقِيفٍ أَسْلَمَ وَعِنْدَهُ عَشْرُ نِسْوَةٍ حِينَ أَسْلَمَ الثَّقَفِيُّ ‏ "‏ أَمْسِكْ مِنْهُنَّ أَرْبَعًا وَفَارِقْ سَائِرَهُنَّ ‏"‏ ‏.‏
USC-MSA web (English) reference : Book 29, Hadith 76
Arabic reference : Book 29, Hadith 1238