It is narrated from Hazrat Ziyad bin Harith (may Allah be pleased with him) that once he gave the adhan. At the time of iqamah, Hazrat Bilal (may Allah be pleased with him) intended to say the iqamah, so the Prophet (peace and blessings be upon him) said, "O caller brother! The person who gives the adhan should also say the iqamah."