عن ابي هريرة قال بينا رسول الله ﷺ جالس على باب من أبواب المسجد مرت إمرأة على دابة فلما حاذت بالنبي ﷺ عثرت بها فأعرض النبي ﷺ وتكشفت فقيل يا رسول الله إن عليها سراويل فقال رحم الله المتسرولات
الجامع لشعب الايمان للبيهقي الرابع والخمسون من شعب الايمان وهو باب في ألحياء بفضوله فصل في حجاب النساء والتغليظ في سترهن
From Abu Huraira who said: While the Messenger of Allah (SAW) was sitting at one of the doors to the mosque, a woman came by riding on an animal, and when it passed the Prophet (SAW), it tripped with her on it; the Prophet (SAW) turned away while she was exposed. Someone said: Oh Messenger of Allah she’s wearing undergarments! He said: May Allah have mercy on women who wear undergarments.
Al-Bayhaqi, Al-jami’ Li-sha’b Al-iman [The Collection of the Branches of Belief], The fifty-fourth of the branches of belief, this is, the section regarding modesty in one’s inquisitiveness, Subsection: regarding the veiling of women and thickening their coverings