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." (RU)
App reference (RU): Book 14, Hadith 38 (RU)
English reference (RU): Vol. 2, Book 14, Hadith 1402 (RU)
Arabic reference (RU): Book 14, Hadith 1412 (RU)