Overview
According to the Encyclopedia of Islam and the Muslim World, the meaning of hijab has evolved over time:
The term hijab or veil is not used in the Qur'an to refer to an article of clothing for women or men, rather it refers to a spatial curtain that divides or provides privacy. The Qur'an instructs the male believers (Muslims) to talk to the wives of the Prophet Muhammad behind a hijab. This hijab was the responsibility of the men and not the wives of Prophet Muhammad. However, in later Muslim societies this instruction, specific to the wives of Prophet Muhammad, was generalized, leading to the segregation of Muslim men and women. Modesty in the Qur'an concerns both men's and women's gaze, gait, garments, and genitalia. Clothing for women involves khumūr over the necklines and jilbab (cloaks) in public so that they may be identified and not harmed. Guidelines for covering of the entire body except for the hands, the feet and the face, are found in texts of fiqh and hadith that are developed later. For men, hijab includes the wearing of modest clothing (not very attractive).The Arabic word literally means curtain or cover (noun). Most Islamic legal systems define this type of modest dressing as covering everything except the face and hands in public. Some interpretations say that a veil is not compulsory in front of blind, asexual or gay men.
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