Musnad Ahmad 32:1743

'Affan narrated to us, Hammam narrated to us, from Qatadah, who said: I asked Anas, "How many times did the Messenger of Allah (peace and blessings of Allah be upon him) perform 'Umrah?" He said: "He performed 'Umrah four times: his 'Umrah from which the polytheists turned him away in Dhu al-Qa'dah; his 'Umrah also in the following year in Dhu al-Qa'dah; his 'Umrah when he distributed the spoils of Hunayn from al-Ji'ranah in Dhu al-Qa'dah; and his 'Umrah with his Hajj."