Sayyiduna Abu Darda (may Allah be pleased with him) says: One day, the Messenger of Allah (peace and blessings be upon him) was sitting on the pulpit, then he (peace and blessings be upon him) delivered a sermon to the people and recited a verse in between. Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him) was sitting beside me. I said to him: O Ubayy! When was this verse revealed? But he refused to speak to me. I repeated the question, but he still refused to talk to me. When the Messenger of Allah (peace and blessings be upon him) descended from the pulpit, Sayyiduna Ubayy (may Allah be pleased with him) said to me: You will get nothing from the reward of this Friday except that which you engaged in idle talk. When the Noble Prophet (peace and blessings be upon him) finished the prayer, I went to him (peace and blessings be upon him) and informed him that O Messenger of Allah, you recited a verse (during the sermon), while Sayyiduna Ubayy bin Ka'b (may Allah be pleased with him) was sitting beside me, so I asked him when this verse was revealed, but he refused to speak to me. When you descended, Ubayy (may Allah be pleased with him) said to me that I have no reward for Friday except that which I engaged in idle talk. Upon hearing this, he (peace and blessings be upon him) said: Ubayy has spoken the truth. When you hear your Imam speaking, remain silent until he finishes.