Maqsim bin Bajra مقسم بن بجرة · The Book of Fasting

"I went out with Abu Qilabah on a journey and he brought some food. I said: 'I am fasting.' He said: 'The Messenger of Allah went out on a journey and brought some food, and said to a man: Come and eat. He said: I am fasting. He said: Allah has waived for the traveler half of the prayer and fasting when traveling, so come and eat. So I came close and ate."'

"It is said that fasting while traveling is like not fasting while a resident." (Daif)