Sayyiduna Abu Umaymah (may Allah be pleased with him) said: The Prophet (peace and blessings be upon him) was eating a meal on a journey, and I was sitting near him (peace and blessings be upon him). He (peace and blessings be upon him) said: "Come and have the meal." I said: I am fasting. He (peace and blessings be upon him) said: "Allah has relieved the traveller of half of the prayer and of fasting."
Hadith Referenceالمعجم الكبير للطبراني / مسند من يعرف بالكنى / 19112