Musnad Ahmad 658:36

Bahz narrated to us, Shu'bah narrated to us, 'Adi ibn Thabit narrated to us, from Al-Bara': "The Messenger of Allah (peace and blessings of Allah be upon him) was on a journey, and he recited in the last 'Isha' prayer in one of the two rak'ahs: 'By the Fig and the Olive' (At-Tin)."