Yahya related to me from Malik from Abu'z Zinad from al-Araj fromAbu Hurayra that the Messenger of Allah, may Allah bless him and granthim peace, said, "Even saying to your companion 'Listen' while theimam is giving the khutba on the day of jumua, is to speak foolishly."
USC-MSA web (English) reference: Book 5, Hadith 6
Arabic reference: Book 5, Hadith 231