Musnad Ahmad 1013:43

'Ali ibn Bahr narrated to us, 'Isa ibn Yunus narrated to us, Mus'ab ibn Thabit narrated to us, from Abu Hazim, from Sahl ibn Sa'd al-Sa'idi, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "The believer is a place of affection, and there is no good in one who does not show affection and is not shown affection."