Sunan an-Nasa'i 2261
سنن النسائي#2261Sahihأَخْبَرَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، عَنْ عُثْمَانَ بْنِ عُمَرَ، قَالَ أَنْبَأَنَا عَلِيُّ بْنُ الْمُبَارَكِ، عَنْ يَحْيَى، عَنْ مُحَمَّدِ بْنِ عَبْدِ الرَّحْمَنِ، عَنْ رَجُلٍ، عَنْ جَابِرٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " لَيْسَ مِنَ الْبِرِّ الصِّيَامُ فِي السَّفَرِ " .
It was narrated from a man, from Jabir that the Messenger of Allah said:"It is not righteousness to fast when traveling
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiHasan
In-book reference: 22:172