It was narrated from Abu Hurairah that:
The Messenger of Allah (ﷺ) said: "Whoever says to his companion on Friday, when the imam is delivering the khutbah: 'Listen attentively,' has engaged in idle talk." (ID)
App reference (ID): Book 14, Hadith 38 (ID)
English reference (ID): Vol. 2, Book 14, Hadith 1402 (ID)
Arabic reference (ID): Book 14, Hadith 1412 (ID)