Ali bin al-Madini علي بن المديني · The Book of Fasting

"It is not righteousness to fast when traveling."

"I came to the Messenger of Allah and the Messenger of Allah said to me: 'Stay and have a meal for breakfast, O Abu Umayyah.' I said: I am fasting.' He said: 'Come and I will tell you about the traveler. Allah has waived meaning the fasting and half the prayer for him."'