Muhammad bin Aban bin Wzyr محمد بن أبان بن وزير البلخي · The Book of Fasting

"I was traveling and I came to the Prophet when I was fasting, and he was eating. He said:'Come (and eat).' I said: 'I am fasting.' He said: 'Come here; do you not 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."