"Narrated 'Aisha: The wives of the Prophet used to go to Al-Manasi, a vast plateau, to answer the call of nature at night. 'Umar used to say to the Prophet, "Let your wives be veiled," but Allah's Apostle did not do so. One night Sauda bint Zam'a the wife of the Prophet went out at 'Isha' time and she was a tall lady. 'Umar addressed her and said, "I have recognized you, O Sauda." He said so, as he was anxious for some Divine orders regarding the veil. So Allah revealed the verses of the veil."