It wasnarrated that Ibn 'Umar said:
"At the time of the Messenger ofAllah (ﷺ) we used to eat while walking, and drink while standingup." (RU)
English reference (RU): Vol. 4, Book 29, Hadith 3301 (RU)
Arabic reference (RU): Book 29, Hadith 3426 (RU)