Abdul Razzaq al-Badr said,
The head-cover referred to here is a cloth that is put over the head to protect the turban from the stains of oil.
Al-Bajūrī said,
The head-cover (Arabic: qinā’) refers, in its broader meaning, to the sheet that a person places upon the turban and which partially covers the face. However in the context of this chapter, it refers to the cloth worn underneath the turban to protect it from the stains of oil or the heat.
126. Anas ibn Mālik narrated: “Allāh’s Messenger (peace be upon him) often wore a cloth on his head. This cloth, because of its greasiness, looked as if it had been oiled.” [146]
Al-Bajūrī said,
The benefits of covering the turban with a sheet so that it covers most of the face are many, some of them are: it is a sign of one’s shyness and fear of Allāh because it is the habit of the fearful to hide and cover themselves, it helps the heart to be more attentive to Allāh and not distracted by the surroundings, it gives the person [the opportunity] to have a minor solitude, as some Sufis have said.