Narrated 'Aishah (RA):

While on a journey, the Prophet (ﷺ) used to shorten the prayer (sometimes) and offer it completely (sometimes). Similarly, he used to observe fast (sometimes) and break it (sometimes). [ad-Daraqutni reported it, and its narrators are reliable, but it is a defective Hadith].

وَعَنْ عَائِشَةَ رَضِيَ اَللَّهُ عَنْهَا; { أَنَّ اَلنَّبِيَّ ‏- صلى الله عليه وسلم ‏-كَانَ يَقْصُرُ فِي اَلسَّفَرِ وَيُتِمُّ, وَيَصُومُ وَيُفْطِرُ.‏ } رَوَاهُ اَلدَّارَقُطْنِيُّ, وَرُوَاتُهُ ثِقَاتٌ.‏ إِلَّا أَنَّهُ مَعْلُول ٌ [1]‏ .‏