Musnad Ahmad 124:8

Abdullah ibn Ahmad said: Suwayd ibn Sa'id and Abu Ibrahim al-Turjumani narrated to me, they said: Abd al-Aziz ibn Abi Hazim narrated to us, from his father, from Sahl ibn Sa'd, he said: I heard the Prophet, peace and blessings of Allah be upon him, saying: "A space the size of a whip in Paradise is better than the world and what is in it. And a morning journey that a servant takes in the path of Allah is better than the world and what is in it."