Sahih al Bukhari 6456
To make the Heart Tender (Ar-Riqaq)
حَدَّثَنِي أَحْمَدُ بْنُ أَبِي رَجَاءٍ، حَدَّثَنَا النَّضْرُ، عَنْ هِشَامٍ، قَالَ أَخْبَرَنِي أَبِي، عَنْ عَائِشَةَ، قَالَتْ كَانَ فِرَاشُ رَسُولِ اللَّهِ صلى الله عليه وسلم مِنْ أَدَمٍ، وَحَشْوُهُ مِنْ لِيفٍ.
Narrated `Aisha:The bed mattress of the Prophet (ﷺ) was made of a leather case stuffed with palm fibres
Text from the public-domain hadith-api dataset. Numbering follows that dataset and can differ by a few from some printed editions — check the wording, not only the number.