Mu'adh bin Anas Al-Juhani (May Allah be pleased with him) said:
The Prophet (ﷺ) forbade (us) from sitting with our legs drawn up to our belly (Ihtiba') during the Friday Khutbah (religious talk before the prayer).[Abu Dawud and At-Tirmidhi]. (RU)
App reference (RU): Book 18, Hadith 195 (RU)
Arabic/English book reference (RU): Book 18, Hadith 1705 (RU)