Sunan an-Nasa'i

It was narrated from Ayyub, from a Shailh of Qushair, from his paternal uncle; then we met him concerning some camels of his, and Bu Qilabah said to him: "Tell it to us." The old man said: "My paternal uncle told me that he went to the Prophet, concerning some camels of his, while he was eating. He said: “Come and eat.' I said: “I am fasting.' He said: “Allah, the mighty and sublime, has waived half of the prayer and fasting for the traveler, the pregnant woman and the sick”””"