What portion of the turban must be wiped for validity?
Chapter on Wiping over the Khuffayn (Leather Socks)
Al-Mughni
Book of Purification
Primary text
Wiping a portion of the turban is sufficient, analogous to the permissibility of wiping only a portion of the khuff. This sufficiency specifically applies to the 'akwar' (the circular layers) and not the middle section.
Supporting text
If one wipes only the middle section of the turban, there are two opinions: one holds that it suffices, similar to wiping a portion of the circular layers, and the second holds that it does not suffice, similar to wiping only the underside of the khuff.