Sahih Muslim 2638 b
Abu Huraira narrated directly from Allah's Messenger (ﷺ) that he said:
People are like mines of gold and silver; those who were excellent in Jahiliya (during the days of ignorance) are excellent In Islam, when they have, an understanding, and the souls are troops collected together and those who had a mutual familiarity amongst themselves in the store of prenatal existence would have affinity amongst them, (in this world also) and those who opposed one of them, would be at variance with one another.
حَدَّثَنِي زُهَيْرُ بْنُ حَرْبٍ، حَدَّثَنَا كَثِيرُ بْنُ هِشَامٍ، حَدَّثَنَا جَعْفَرُ بْنُ بُرْقَانَ، حَدَّثَنَا 
 يَزِيدُ بْنُ الأَصَمِّ، عَنْ أَبِي هُرَيْرَةَ، بِحَدِيثٍ يَرْفَعُهُ قَالَ ‏
"‏ النَّاسُ مَعَادِنُ كَمَعَادِنِ الْفِضَّةِ وَالذَّهَبِ
 خِيَارُهُمْ فِي الْجَاهِلِيَّةِ خِيَارُهُمْ فِي الإِسْلاَمِ إِذَا فَقُهُوا وَالأَرْوَاحُ جُنُودٌ مُجَنَّدَةٌ فَمَا تَعَارَفَ
 مِنْهَا ائْتَلَفَ وَمَا تَنَاكَرَ مِنْهَا اخْتَلَفَ ‏"‏ ‏.‏