Is it legislated for a disbeliever to shave his head upon embracing Islam, and is it obligatory or recommended? And is the same legislated for an apostate upon returning to Islam? And what should he do if his hair is short?

It has not been authentically reported from the Prophet, peace and blessings be upon him, that he commanded a new Muslim to shave his hair. The hadiths reported concerning this are weak, even if some later scholars deemed them hasan (good). The majority of scholars recommend that a new Muslim shave his head. Some of them held that this ruling is specific to hair that is a distinctive emblem of disbelievers, and this is the closer (more accurate) view. No text has been reported regarding the shaving of an apostate's hair if he embraces Islam, but he may be commanded to shave it if his apostasy was prolonged and his hair became an emblem of disbelief.