The Azan and Iqaamah

I saw Bilāl going out to Al-Abtah to make Adhān. When he reached: "Come to prayer! Come to success!" He turned his neck right and left and did not turn around

The Muezzin is responsible for the Adhān, and the leader of the congregation is responsible for the Iqāmah

Bilāl made a call to prayer before the break of dawn. The Prophet (may Allah's peace and blessings be upon him) therefore commanded him to return and make a call: Lo! The slave of Allah slept. Lo! The slave of Allah slept