At the same time as the marriage of the Messenger of Allah (peace be upon him) with Zainab (may Allah be pleased with her), the ayah (verse) on hijab (veil) was revealed. After the wedding reception, a group of people stayed behind to talk in the Messenger of Allah’s home. The Messenger of Allah (peace be upon him) was with them as well as his wife, who was directing her face to the wall. The gathering tired the Messenger of Allah (peace be upon him), so he left to greet his other wives and then returned. When the people saw the Messenger of Allah (peace be upon him) again, they realized that they had tired him by staying. Therefore they all left, except Anas ibn Malik, who told us about what happened, saying, “The Messenger of Allah (peace be upon him) returned to [his home] and pulled the curtain [between him and me]. I stayed in the [outer section of the] room. After the Messenger of Allah (peace be upon him) had rested a short while, he came out to me. Allah (Glorified be He) revealed an ayah to the Messenger of Allah (peace be upon him) at that time, so the Messenger of Allah (peace be upon him) left to tell the ayah to the people. Allah says (glorified be He) in this ayah, {O you who have believed, do not enter the houses of the Prophet without permission, nor stay waiting for the meal time; but if you are invited to meals, do come, and when you have taken food, disperse; do not stay to engage in talks, for such behavior causes trouble to the Prophet but he is shy of [saying anything to] you. However, Allah is not shy of [telling] the truth. If you have to ask the wives of the Prophet for something, ask for it from behind a curtain. This is purer for your hearts as well as their hearts} [Surah Al-Ahzab: 53] [related by Muslim]. This ayah only talks about the wives of the Messenger of Allah (peace be upon him), but then Allah revealed, {O Prophet, enjoin your wives and daughters and the women of the believers that they should let down their outer-garments over them (when in public); this makes it more likely that they will be recognized (i.e. respected) and not harassed. Allah is Forgiving and Merciful} [Surah Al-Ahzab: 59], and the hijab became obligatory for all the Muslim women.