A woman’s whole body is to be covered except her hands and face, unless is praying in front of an unrelated (non-maḥram) man - in which case, she is to cover everything. This is because the Prophet (May Allāh praise him and Peace be upon him) said, “Women are ‘awrah” [Authenticated by Sheikh Al Albānī in Al Irwā`: 273]. [Al Fiqh Al Muyassar (Islamic Jurisprudence Made Easy): 61]