Sahih Muslim 1118 a
Humaid reported that Anas (Allah be pleased with him) was asked about fasting during Ramadan while travelling. He said:
We travelled with the Messenger of Allah (ﷺ) during the month of Ramadan, but neither the observer of the fast found fault with the breaker of the fast, nor the breaker of the fast found fault with the observer of the fast.
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، أَخْبَرَنَا أَبُو خَيْثَمَةَ، عَنْ حُمَيْدٍ، قَالَ سُئِلَ أَنَسٌ - رضى الله عنه - عَنْ صَوْمِ رَمَضَانَ فِي السَّفَرِ فَقَالَ سَافَرْنَا مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم فِي رَمَضَانَ فَلَمْ يَعِبِ الصَّائِمُ عَلَى الْمُفْطِرِ وَلاَ الْمُفْطِرُ عَلَى الصَّائِمِ ‏.‏