From Sahih Bukhari (Hadith 5915):
Narrated Ibn `Umar:I heard Allah's Messenger (ﷺ), while he was in the state of Ihram and his hair was stuck together with gum, saying, "Labbaik, Allahumma Labbaik, Labbaik La Sharika laka Labbaik. Inn-al-Hamda Wan-Ni'mata Laka wal-Mulk, La Sharika Lak." He did not add anything to those words
Reference: Bukhari 5915