Musnad Abu Ya'la al-Mawsili 111:22

Abu Ya'la informed us, Jabarah ibn Mughallis narrated to us, Sharik and Abu Shihab narrated to us, from 'Asim, from al-Sha'bi, from Ibn 'Abbas: That the Prophet (peace and blessings of Allah be upon him) was brought a bucket of Zamzam while he was performing Tawaf, and he drank while he was standing.