Musnad Ahmad 32:1405

Narrated to us Muhammad ibn Mus'ab, narrated to us al-Awza'i, from Ayyub ibn Musa, from Abdullah ibn Umayr, from Thabit, from Anas, who said: I was at the callosities of the she-camel of the Messenger of Allah, peace and blessings of Allah be upon him, when he said: "Labbayk (I am present) for Hajj and Umrah together." And that was during the Farewell Pilgrimage.