Musnad Abu Ya'la al-Mawsili 251:6

Abu Bakr ibn Abi Shaybah narrated to us, Ubayd Allah ibn Musa narrated to us, Dawud al-A'raj narrated to us, from al-Sha'bi, from Jarir ibn Abdullah, who said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: "Islam is built upon five: the testimony that there is no god but Allah, the establishment of prayer, the giving of zakat, the pilgrimage to the House, and the fasting of Ramadan."