It wasnarrated from 'Amr bin Shu'aib, from his father, that hisgrandfather said:
"The Messenger of Allah (ﷺ) forbade Ihtiba' (sitting with one's thighs gathered up against the stomach while wrapping one's arm or garment around them) onFridays, meaning, when the Imam is delivering the sermon."
English reference: Vol. 1, Book 5, Hadith 1134
Arabic reference: Book 5, Hadith 1188