Narrated Abu Sa`id Al-Khudri: The Prophet (ﷺ) forbade Ishtimal-as-Samma' and that a man should sit in an Ihtiba' posture in one garment, nothing of which covers his private parts
Book 77 · Hadith 39
صحيح البخاري
Narrated Abu Sa`id Al-Khudri: The Prophet (ﷺ) forbade Ishtimal-as-Samma' and that a man should sit in an Ihtiba' posture in one garment, nothing of which covers his private parts