Sahih Muslim
The Book of Virtue, Good Manners and Joining of the Ties of Relationship (Kitab Al-Birr was-Salat-I-wal-Adab)
Book Number: 032 / Hadith Number: 6376
Abu Huraira reported Allah's Messenger (may peace be upon him) Saying: Souls are troops collected together and those who familiarised with each other (in the heaven from where these come) would have affinity, with one another (in the world) and those amongst them who opposed each other (in the Heaven) would also be divergent (in the world).