Obligations of Prayer

Assalamu alaykumWe notice that numerous Hanafies and Shafies supplicate in congregation after the compulsory prayers. Can Mufti please enlighten us on this issue in light of what is mentioned in their books and thereafter show us what is the correct Sunnah.

Salam, my question is in Salah. In Sujoud, when the forehead touches the ground; is it valid if the forehead is covered or partially covered by a hat? Or does the forehead has to be bare to the ground? Jazaka Allahu khayran.