Sahih Bukhari | Volume 1 | Hadith Number 606

Narrated by 'Aun bin Abi Juhaifa
My father said, "I saw Allah's Apostle at a place called Al-Abtah. Bilal came and informed him about the prayer and then came out with an Anza and planted it in front of Allah's Apostle at Al-Abtah and pronounced the Iqama."