Musnad Ahmad 1013:44

Husayn ibn Muhammad narrated to us, Muhammad ibn Mutarrif narrated to us, from Abu Hazim, from Sahl, that he heard the Messenger of Allah (peace and blessings of Allah be upon him) saying: "My pulpit is upon a *tur'ah* (gate/opening) from the *tur'at* (gates/openings) of Paradise." I said to him, "What is the *tur'ah*, O Abu al-Abbas?" He said, "The door."