The narrator says: I asked him (Hamzah, may Allah be pleased with him) about fasting while travelling, and he said: We used to both fast and break our fast while travelling, and the one not fasting would not find fault with the one fasting, nor the one fasting with the one not fasting.
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2984