Musannaf Ibn Abi Shayba 18:637

Abu Bakr narrated to us, he said: Waki' narrated to us, he said: Mis'ar narrated to us, from Wasil al-Ahdab al-Asadi, from al-Sha'bi, from Ali, that he used to cut the *kanaf* (palm-leaf coverings/partitions) or he would order them to be cut.