Musa bin Abi Aa'isha موسى بن أبي عائشة · The Book of Fasting

"I came to the Prophet to discuss something and he was eating breakfast. He said: 'Come and eat.' I said: 'I am fasting.' He said: 'Come and I will tell you about fasting. Allah has waived half of prayer and fasting from the traveler, and he has granted a concession to pregnant women and the sick."'