حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ عَائِشَةَ، زَوْجَ النَّبِيِّ صلى الله عليه وسلم كَانَتْ تُصَلِّي فِي الدِّرْعِ وَالْخِمَارِ .
Yahya related to me from Malik that he had heard that A'isha, the wife of the Prophet (ﷺ) used to pray in a shift and head-covering.
Reference: Sunnah.com : Book 8, Hadith 36
USC-MSA web (English) : Book 8, Hadith 36
Arabic : Book 8, Hadith 325