It is narrated from Sayyidah Aishah (may Allah be pleased with her) that Hamzah, a man from the tribe of Aslam, said: "O Messenger of Allah, I fast continuously and do not break my fast; should I fast while travelling too?" He (peace and blessings be upon him) said: "If you wish, fast; and if you wish, break your fast."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2961