Musnad Ahmad 937:6

Ahmad ibn al-Hajjaj narrated to us, Abdullah narrated to us, Ibn Lahi'ah informed us, Yazid ibn Abi Habib narrated to us: That Abu Salim al-Jayshani came to Abu Umayyah in his house and said: "I heard Abu Dharr saying that he heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: 'If one of you loves his companion, let him come to him in his house and inform him that he loves him for the sake of Allah.' And I have come to you in your house."