It was narrated from 'Abdullah bin Ibrahim bin Qariz and Sa'eed bin Al-Musayyab that:
Abu Hurairah said: "I heard the Messenger of Allah (ﷺ) say: 'If you say to your companion: Listen attentively on a Friday when the Imam is delivering the khutbah, then you have engaged in idle talk.'" (ID)
App reference (ID): Book 14, Hadith 39 (ID)
English reference (ID): Vol. 2, Book 14, Hadith 1403 (ID)
Arabic reference (ID): Book 14, Hadith 1413 (ID)