Sayyiduna al-Sa'ib bin Yazid (may Allah be pleased with him) said: In the time of the Messenger of Allah (peace and blessings be upon him) and of Sayyiduna Abu Bakr and Umar (may Allah be pleased with them both), the adhan was given beside the pulpit, and the first to introduce the last adhan (the third adhan) was Sayyiduna Uthman (may Allah be pleased with him).
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6616