Yahya related to me from Malik from Ibn Shihab that Thalaba ibn Abi Malik al Quradhi informed him that in the time of Umar ibn al Khattab they used to pray on the day of jumua until Umar came out, and when Umar came out and sat on the mimbar and the muadhdhins called the adhan, they would sit and talk, and then when the muadhdhins were silent and Umar stood to give the khutba, they would pay attention and no-one would speak .

Ibn Shihab said, "The imam coming out stops prayer and his speaking stops conversation."
Muwatta Malik Book 5, Hadith 7
← Previous Hadith Yahya related to me from Malik from Abu'z Zinad from al-Araj from Abu Hurayra that the Messenger of Allah, may Allah bless him and grant him peace, said, "Even saying to your companion 'Listen' while the imam is giving the khutba on the day of jumua, is to speak foolishly."

Muwatta Malik Book 5, Hadith 6 Next Hadith → Yahya related to me from Malik from Abu'n Nadr, the mawla of Umar ibn Ubaydullah, from Malik ibn Abi Amir that Uthman ibn Affan used to say in khutbas, and he would seldom omit it if he was giving the khutba, "When the imam stands delivering the khutba on the day of jumua, listen and pay attention, for there is the same portion for someone who pays attention but cannot hear as for someone who pays attention and hears. And when the iqama of the prayer is called, straighten your rows and make your shoulders adjacent to each other, because the straightening of the rows is part of the completion of the prayer." Then he would not say the takbir until some men who had been entrusted with straightening the rows came and told him that they were straight. Then he would say the takbir.

Muwatta Malik Book 5, Hadith 8