We were with the Prophet ﷺ on one of his military expeditions during Ramadan. One of the Prophet's companions ﷺ was fasting and grew so weak that thirst nearly killed him, and his she-camel began wandering under the thorny trees.The Prophet ﷺ was told about him and said, "Bring him to me."When the man was brought, he said, "Are you not on the path of Allah and in the company of the Messenger of Allah ﷺ? Break your fast."So the man broke his fast.
حدثنا روح حدثنا زكريا حدثنا أبو الزبير أنه سمع
كنا مع النبي ﷺ في غزوة غزاها وذلك في رمضان فصام رجل من أصحاب النبي ﷺ فضعف ضعفا شديدا وكاد العطش أن يقتله وجعلت ناقته تدخل تحت العضاه فأخبر به النبي ﷺ فقال ائتوني به فأتي به فقال ألست في سبيل الله ومع رسول الله ﷺ أفطر فأفطر
Its chain of transmission is sahih. It is found in Darimi with a similar wording, 2/16, in the Book of Fasting, on fasting while traveling. And Tabarani in Al-Kabir, 11/187, no. 11447. Its meaning has already been mentioned under "It is not righteousness to fast while traveling."