Language:
كتاب الغسل
5  
Bathing (Ghusl)
(20)
Chapter: Whosoever took a bath alone (in seclusion) completely naked
(20)
باب مَنِ اغْتَسَلَ عُرْيَانًا وَحْدَهُ فِي الْخَلْوَةِ، وَمَنْ تَسَتَّرَ فَالتَّسَتُّرُ أَفْضَلُ
Sahih al-Bukhari 278

Narrated Abu Huraira:

The Prophet (ﷺ) said, 'The (people of) Bani Israel used to take bath naked (all together) looking at each other. The Prophet (ﷺ) Moses used to take a bath alone. They said, 'By Allah! Nothing prevents Moses from taking a bath with us except that he has a scrotal hernia.' So once Moses went out to take a bath and put his clothes over a stone and then that stone ran away with his clothes. Moses followed that stone saying, "My clothes, O stone! My clothes, O stone! till the people of Bani Israel saw him and said, 'By Allah, Moses has got no defect in his body. Moses took his clothes and began to beat the stone." Abu Huraira added, "By Allah! There are still six or seven marks present on the stone from that excessive beating."

حَدَّثَنَا إِسْحَاقُ بْنُ نَصْرٍ، قَالَ حَدَّثَنَا عَبْدُ الرَّزَّاقِ، عَنْ مَعْمَرٍ، عَنْ هَمَّامِ بْنِ مُنَبِّهٍ، عَنْ أَبِي هُرَيْرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏ "‏ كَانَتْ بَنُو إِسْرَائِيلَ يَغْتَسِلُونَ عُرَاةً، يَنْظُرُ بَعْضُهُمْ إِلَى بَعْضٍ، وَكَانَ مُوسَى يَغْتَسِلُ وَحْدَهُ، فَقَالُوا وَاللَّهِ مَا يَمْنَعُ مُوسَى أَنْ يَغْتَسِلَ مَعَنَا إِلاَّ أَنَّهُ آدَرُ، فَذَهَبَ مَرَّةً يَغْتَسِلُ، فَوَضَعَ ثَوْبَهُ عَلَى حَجَرٍ، فَفَرَّ الْحَجَرُ بِثَوْبِهِ، فَخَرَجَ مُوسَى فِي إِثْرِهِ يَقُولُ ثَوْبِي يَا حَجَرُ‏.‏ حَتَّى نَظَرَتْ بَنُو إِسْرَائِيلَ إِلَى مُوسَى، فَقَالُوا وَاللَّهِ مَا بِمُوسَى مِنْ بَأْسٍ‏.‏ وَأَخَذَ ثَوْبَهُ، فَطَفِقَ بِالْحَجَرِ ضَرْبًا ‏"‏‏.‏ فَقَالَ أَبُو هُرَيْرَةَ وَاللَّهِ إِنَّهُ لَنَدَبٌ بِالْحَجَرِ سِتَّةٌ أَوْ سَبْعَةٌ ضَرْبًا بِالْحَجَرِ‏.‏
Reference : Sahih al-Bukhari 278
In-book reference : Book 5, Hadith 30
USC-MSA web (English) reference : Vol. 1, Book 5, Hadith 277
  (deprecated numbering scheme)