Narrated Muhammad bin Abi Bakr Al-Thaqafi:
While we were going from Mina to ‘Arafat, I asked Anas bin Malik, about Talbiya, “How did you use to say Talbiya in the company of the Prophet?” Anas said: “People used to say Talbiya and their saying was not objected to and they used to say Takbir and that was not objected to either. ”
Sahih Bukhari, Volume 2, Book15, Number 87