Musnad Ahmad 1153:1900

Abu Mu'awiyah narrated to us, Al-A'mash narrated to us, from 'Umarah, from Abu 'Atiyyah, from 'Aishah, who said: The Talbiyah of the Prophet, peace and blessings of Allah be upon him, was three times. He would say: "Labbayk Allahumma Labbayk, Labbayka la sharika laka Labbayk, inna al-hamda wa an-ni'mata laka" (Here I am, O Allah, here I am; here I am, You have no partner, here I am; indeed, all praise and grace belong to You).