"I was traveling and I came to the Prophet when he was eating and I was fasting. He said: 'Come and eat.' I said: 'I am fasting.' He said: 'Do you know what Allah has waived for the traveler?' he said: 'Do you know what Allah has waived for the traveler?' I said: 'What has Allah waived for the traveler?' He said: 'Fasting and half of the prayer."'
Sunan an-Nasa'i Book 22, Hadith 192