Abu Darda reported,

The Messenger of Allah ﷺ sat on the pulpit one day and addressed the people, and he recited a verse. Ubayy bin Kaab was beside me, so I said to him, "Ubayy, when was this verse revealed?"He refused to speak to me. I asked him again, but he still refused to answer until the Messenger of Allah ﷺ descended from the pulpit. Then Ubayy said to me, "You have gained nothing from your Friday prayer except the idle talk you engaged in."When the Messenger of Allah ﷺ finished, I went to him and told him what had happened. I said, "Messenger of Allah, you recited a verse while Ubayy bin Kaab was beside me, so I asked him when this verse had been revealed, but he refused to speak to me. When you came down, Ubayy claimed that I had gained nothing from my Friday prayer except the idle talk I engaged in."The Prophet ﷺ said, "Ubayy spoke the truth. When you hear your imam speaking, remain silent until he is finished."

حدثنا مكي حدثنا عبد الله بن سعيد عن حرب بن قيس

عن أبي الدرداء قال

جلس رسول الله ﷺ يوما على المنبر فخطب الناس وتلا آية وإلى جنبي أبي بن كعب فقلت له يا أبي متى أنزلت هذه الآية قال فأبى أن يكلمني ثم سألته فأبى أن يكلمني حتى نزل رسول الله ﷺ فقال لي أبي ما لك من جمعتك إلا ما لغيت فلما انصرف رسول الله ﷺ جئته فأخبرته فقلت أي رسول الله إنك تلوت آية وإلى جنبي أبي بن كعب فسألته متى أنزلت هذه الآية فأبى أن يكلمني حتى إذا نزلت زعم أبي أنه ليس لي من جمعتي إلا ما لغيت فقال صدق أبي فإذا سمعت إمامك يتكلم فأنصت حتى يفرغ