Sahih al-Bukhari 1905
Book 30: Fasting · Narrated by 'Alqama
Arabic
حَدَّثَنَا عَبْدَانُ، عَنْ أَبِي حَمْزَةَ، عَنِ الأَعْمَشِ، عَنْ إِبْرَاهِيمَ، عَنْ عَلْقَمَةَ، قَالَ بَيْنَا أَنَا أَمْشِي، مَعَ عَبْدِ اللَّهِ ـ رضى الله عنه ـ فَقَالَ كُنَّا مَعَ النَّبِيِّ صلى الله عليه وسلم فَقَالَ " مَنِ اسْتَطَاعَ الْبَاءَةَ فَلْيَتَزَوَّجْ، فَإِنَّهُ أَغَضُّ لِلْبَصَرِ وَأَحْصَنُ لِلْفَرْجِ، وَمَنْ لَمْ يَسْتَطِعْ فَعَلَيْهِ بِالصَّوْمِ، فَإِنَّهُ لَهُ وِجَاءٌ ".
English translation
Narrated 'Alqama:While I was walking with `Abdullah he said, "We were in the company of the Prophet (ﷺ) and he said, 'He who can afford to marry should marry, because it will help him refrain from looking at other women, and save his private parts from committing illegal sexual relation; and he who cannot afford to marry is advised to fast, as fasting will diminish his sexual power
Reference: Sahih al-Bukhari 1905, Book of Fasting. English translation by Dr. Muhammad Muhsin Khan.