Is wearing a topi or turban sunnah?

“Fataawa Mahmoodiyyah states that it is Sunnah to wear a turban. However, by persisting upon a Mustahab act (such as regarding it as necessary to always wear an Amaamah), the act becomes Makrooh.”

“Wearing the topi is a salient feature of Islam from the very era of Rasulullah (Sallallahu Alayhi Wasallam). There are many authentic Ahaadith in support of this. Hence, the Fuqaha have ruled that it is makrooh for one to neglect wearing the topi at the time of salaah and perform salaah bareheaded.”

“It is well established that Rasūlullah Sallallahu Alayhi Wa Sallam used to wear a turban with a tail. While some scholars have mentioned the permissibility of wearing a turban without a tail, we have not come across any authentic and explicit narrations that clearly states Rasūlullah Sallallahu Alayhi Wa Sallam wore a turban …”

“Performing sajdah while the forehead is partially or fully covered by a turban, cap, or winter hat is considered makrūh tanzīhī (mildly disliked) when done without a valid reason. Valid reasons include the ground being excessively cold or hot.”