Musnad Ahmad 30:876

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, he said: I heard al-'Ala' narrating from his father, from Abu Hurayrah, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "The believer, the believer" — two or three times — "is jealous, is jealous, and Allah is more jealous."