Ibn ʿAbbas recited. "No doubt! They fold up their breasts." I said, "O Abu ʿAbbas! What is meant by "They fold up their breasts?" He said, "A man used to feel shy on having sexual relation with his wife or on answering the call of nature (in an open space) so this Verse was revealed:-- "No doubt! They fold up their breasts."
كَانَ الرَّجُلُ يُجَامِعُ امْرَأَتَهُ فَيَسْتَحِي أَوْ يَتَخَلَّى فَيَسْتَحِي فَنَزَلَتْ {أَلاَ إِنَّهُمْ يَثْنُونَ صُدُورَهُمْ}