It is narrated from Tha‘labah bin Abi Malik (may Allah have mercy on him) that he stated: During the time of ‘Umar bin Khattab (may Allah be pleased with him), they used to perform voluntary prayers on Friday until ‘Umar bin Khattab (may Allah be pleased with him) would arrive. When the Imam would come and sit on the pulpit, the muezzin would give the call to prayer while they would be sitting and talking, until the muezzin became silent and ‘Umar (may Allah be pleased with him) would stand up for the sermon; then none of them would speak.
Hadith Referenceمسند الإمام الشافعي / كتاب الجمعة / 425