Musnad Ahmad 929:6

Abdullah narrated to us, Muhammad ibn Abi Bakr al-Muqaddami narrated to us, Abbad ibn Abbad narrated to us, Asim narrated to us, from Abu Uthman, from Ubayy ibn Ka'b, who said: There was a man from the Ansar whose house was the furthest house in Medina, yet he would hardly ever miss a prayer with the Messenger of Allah, peace and blessings of Allah be upon him. I felt sorry for him and said, "O so-and-so, if only you would buy a donkey to protect you from the heat of the burning sand and protect you from the vermin of the earth." He said, "By Allah, I would not like my house to be right next to the house of Muhammad, peace and blessings of Allah be upon him." I took this matter heavily, until I came to the Prophet of Allah, peace and blessings of Allah be upon him, and informed him. He called for the man, and he said the same thing, mentioning that he hoped for reward in his footsteps. The Prophet, peace and blessings of Allah be upon him, said to him: "Indeed, you shall have what you sought reward for."