Language:
كتاب الغسل
5  
Bathing (Ghusl)
(24)
Chapter: A Junub person) can go out and walk in the market or anywhere else
(24)
باب الْجُنُبُ يَخْرُجُ وَيَمْشِي فِي السُّوقِ وَغَيْرِهِ
Sahih al-Bukhari 285

Narrated Abu Huraira:

Allah's Messenger (ﷺ) came across me and I was Junub. He took my hand and I went along with him till he sat down I slipped away, went home and took a bath. When I came back, he was still sitting there. He then said to me, "O Abu Huraira! Where have you been?' I told him about it. The Prophet (ﷺ) said, "Subhan Allah! O Abu Huraira! A believer never becomes impure."

حَدَّثَنَا عَيَّاشٌ، قَالَ حَدَّثَنَا عَبْدُ الأَعْلَى، حَدَّثَنَا حُمَيْدٌ، عَنْ بَكْرٍ، عَنْ أَبِي رَافِعٍ، عَنْ أَبِي هُرَيْرَةَ، قَالَ لَقِيَنِي رَسُولُ اللَّهِ صلى الله عليه وسلم وَأَنَا جُنُبٌ، فَأَخَذَ بِيَدِي، فَمَشَيْتُ مَعَهُ حَتَّى قَعَدَ فَانْسَلَلْتُ، فَأَتَيْتُ الرَّحْلَ، فَاغْتَسَلْتُ ثُمَّ جِئْتُ وَهْوَ قَاعِدٌ فَقَالَ ‏"‏ أَيْنَ كُنْتَ يَا أَبَا هِرٍّ ‏"‏ فَقُلْتُ لَهُ‏.‏ فَقَالَ ‏"‏ سُبْحَانَ اللَّهِ يَا أَبَا هِرٍّ إِنَّ الْمُؤْمِنَ لاَ يَنْجُسُ ‏"‏‏.‏
Reference : Sahih al-Bukhari 285
In-book reference : Book 5, Hadith 37
USC-MSA web (English) reference : Vol. 1, Book 5, Hadith 283
  (deprecated numbering scheme)