The wives of the Prophet (ﷺ) used to go to Al-Manasi, a vast open place (near Baqî at Al-Madîna) to answer the call of nature at night. 'Umar used to say to the Prophet (ﷺ) " Let your wives be veiled, "but Allâh's Messenger (ﷺ) did not do so. One night Sauda bint Zam'a the wife of the Prophet (ﷺ) 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 desired eagerly that the Verses of Al-Hijab (the observing of veils by the Muslim women) may be revealed. So Allâh revealed the Verses of Al-Hijab (a complete body cover excluding the eyes). [1:148-O.B.]