Muhammad bin Abbad reported,

Ibn Abbas recited, "Indeed, they fold up their breasts." I asked, "Abu Abbas, what does 'they fold up their breasts' mean?"He replied, "A man would be intimate with his wife and feel ashamed, or relieve himself and feel ashamed, so this verse was revealed, 'Indeed, they fold up their breasts.'"

Bukhari 4682

Sahih

حدثني إبراهيم بن موسى أخبرنا هشام عن ابن جريج وأخبرني

محمد بن عباد بن جعفر

أن ابن عباس قرأ ألا إنهم تثنوني صدورهم قلت يا أبا العباس ما تثنوني صدورهم قال كان الرجل يجامع امرأته فيستحي أو يتخلى فيستحي فنزلت ألا إنهم تثنوني صدورهم

البخاري 4682صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Bukhari
Book
Tafsir
Chapter
Unquestionably, they fold up their breasts to hide from Him. Unquestionably, when they cover themselves with their garments, He knows what they conceal and what they declare. Indeed, He is Aleem of what is in the breasts.
Numbering
Darussalam 4682
Bukhari 4682