Abu Bahriyyah (may Allah have mercy on him) said: I came to Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) in Sham and said: I love you for the sake of Allah. So he took hold of the front of my garment and pulled me, and said: By Allah? - two or three times - and I said: By Allah. Then he said: I heard the Messenger of Allah (peace and blessings be upon him) say: "My love - or My mercy - is due to those who love one another for My sake, sit together for My sake, visit one another for My sake and give to one another for My sake."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17314