Musnad Ahmad 27:1059

Muhammad ibn Abi ‘Adi narrated to us, from Humayd, from Bakr, from Ibn ‘Umar, who said: The Talbiyah of the Prophet, peace and blessings of Allah be upon him, was: "Labbayk Allahumma Labbayk, Labbayka la sharika laka Labbayk, inna al-hamda, wa an-ni’mata, laka wa al-mulk, la sharika lak." (At your service, O Allah, at your service; at your service, You have no partner, at your service; indeed, all praise and grace belong to You, and the dominion; You have no partner.)