Musnad Ahmad 28:203

Yahya narrated to us, Husayn narrated to us, ‘Amr ibn Shu’ayb narrated to us, from his father, from his grandfather, who said: "I saw the Messenger of Allah (may Allah bless him and grant him peace) praying barefoot and wearing sandals, and he would fast while traveling and break his fast, and he would drink while standing and while sitting, and he would turn away [from the prayer] to his right and to his left."