It is narrated from Sayyiduna Salman (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Souls are like assembled troops: those among them that became acquainted with one another (in the world of souls) come together in affection and love (in this world as well), and those that remained strangers to one another remain in disagreement and estrangement."
Hadith Referenceالمعجم الأوسط / باب الألف / 1577
Hadith Takhrij«أخرجه الطبراني فى «الكبير» برقم: 6169»