Musnad Ahmad 30:1416

'Affan narrated to us, Hammad bin Salamah narrated to us, from Abu Sinan, from 'Uthman bin Abi Sawdah, from Abu Hurairah, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "When a Muslim visits his brother, or calls upon him, Allah the Almighty and Majestic says: 'You have become good, and your walking has become good, and you have taken for yourself a dwelling in Paradise.'"