Imam Al-Nawawi’s Riyad-us-Saliheen
Undesirability of Sitting with Erected Legs during Friday Sermon
1705. Mu`adh bin Anas Al-Juhani (May Allah be pleased with him) said: The Prophet (sallallaahu alayhi wa sallam) 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].