Musnad Ahmad 27:10

Hushaym narrated to us, Humayd informed us, from Bakr ibn Abdullah, from Ibn Umar, who said: The Talbiyah of the Messenger of Allah, peace and blessings of Allah be upon him, was: "Labbayk, Allahumma Labbayk. Labbayk, la sharika laka Labbayk. Inna al-hamda wa an-ni'mata laka wa al-mulk, la sharika lak." And Ibn Umar added to it: "Labbayk, Labbayk wa sa'dayk, wa al-khayru fi yadayk, Labbayk, wa ar-raghba'u ilayka wa al-'amal."