Sahih Muslim Book 4, Hadith Number 1404.

Chapter : Merit of praying in congregation and waiting for prayer.

Ubayy b. Ka’b reported: There was a person among the Ansar whose house was situated at the farthest end of Medina, but he never in missed any prayer along with the Messenger of Allah (may peace be upon him). We felt pity for him and said to him: O, so and so, had you bought a donkey it would have saved you from the burning sand and would have saved you from the reptiles of the earth. He said: Listen I by Allah, I do not like my house to be situated by the side of Muhammad (may peace be upon him). I took (these words of his) ill and came to the Apostle of Allah (may peace be upon him) and informed him about (these words). He (the Holy Prophet) called him and he said exactly like that (which he had mentioned to Ubbay b. Ka’b), but made a mention of this (also) that he wanted a reward for his steps. Upon this the Apostle of Allah (may peace be upon him) said: In fact for you is the reward which you expect.