It was narrated that Ubayy bin Ka'b said: "There was a man among the Ansar whose house was the furthest house in AIMadinah,yet he never missed prayer with the Messenger of Allah P.B.U.H, I felt sorry for him and said: '0 so-and-so, why do you not buy a donkey to spare Yourself the heat of the scorching sand , to carry you over the stony ground, and keep you away from the vermin on the ground?' He said: 'By Allah! I do not want to ve so close to Muhammad P.B.U.H This troubled me until I came to the house of the Prophet P.B.U.H and mentioned that to him. He called (the man) and asked him, and he said something similar, and said that he was hoping for the reward for his steps. The Messenger of Allah P.B.U.H said, 'You will have that (reward) that you sought.'"(Sahih)