Musnad Ahmad 30:2404

Yahya ibn Sa'id narrated to us, from Ibn Abi Dhi'b, he said: Abd al-Rahman ibn Mihran narrated to me, from Abd al-Rahman ibn Sa'd, from Abu Hurayrah, he said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "The farther, then the farther from the mosque, the greater the reward."