Muwatta Malik (Yahya) 230 — on what is reported regarding listening

It is narrated from Thalabah bin Abi Malik Qarzi that people used to perform prayer on the day of Jumu'ah until Sayyiduna Umar bin Khattab, may Allah be pleased with him, would come out. Then when Sayyiduna Umar bin Khattab, may Allah be pleased with him, would come out and sit on the pulpit and the caller to prayer would give the adhan, Thalabah says that we used to sit and talk. When the mu'adhdhin would become silent and Sayyiduna Umar bin Khattab, may Allah be pleased with him, would stand and deliver the sermon, then no one would talk. Ibn Shihab said: When the Imam comes out for the sermon, prayer should be stopped, and when the sermon begins, talking should be stopped.