صحيح البخاري
Sahih Bukhari
كتاب الصوم
The Book of As-Saum (The Fasting).
بَابُ قَوْلِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ لِمَنْ ظُلِّلَ عَلَيْهِ، وَاشْتَدَّ الْحَرُّ: «لَيْسَ مِنَ الْبِرِّ الصَّوْمُ فِي السَّفَرِ»:
(36) Chapter. The saying of the Prophet ﷺ to the person observing Saum (fast) who was being shaded on a very hot day, "It is not from Al-Birr (righteousness) to observe As-Saum (the fast) on a journey."
1 hadith
Hadith 1946
Narrated Jabir bin `Abdullah: Allah's Apostle was on a journey and saw a crowd of people, and a man was being shaded (by them). He asked, "What is the matter?" They said, "He (the man) is fasting." The Prophet said, "It is not righteousness that you fast on a journey."