Musnad Ahmad 30:3469

Yazid ibn Harun narrated to us, Hammad ibn Salamah informed us, from Thabit al-Bunani, from Abu Rafi’, from Abu Hurairah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "A man went out to visit a brother of his in Allah in another village. Allah, the Almighty and Majestic, set an angel in wait upon his path. When he passed by him, he said: 'Where do you intend to go?' He said: 'I intend to go to so-and-so.' He said: 'Is it for a kinship?' He said: 'No.' He said: 'Is it for a favor you have with him that you are repaying?' He said: 'No.' He said: 'Then why are you coming to him?' He said: 'I love him for the sake of Allah, the Almighty and Majestic.' He said: 'Indeed, I am a messenger of Allah to you: that Allah, the Almighty and Majestic, loves you because of your love for him for His sake.'"