Sahih al-Bukhari 2352

Narrated Az-Zuhri:

Anas bin Malik said, that once a domestic sheep was milked for Allah’s Messenger (ﷺ) while he was in the
house of Anas bin Malik. The milk was mixed with water drawn from the well in Anas’s house. A
tumbler of it was presented to Allah’s Messenger (ﷺ) who drank from it. Then Abu Bakr was sitting on his
left side and a bedouin on his right side. When the Prophet (ﷺ) removed the tumbler from his mouth,
`Umar was afraid that the Prophet (ﷺ) might give it to the bedouin, so he said. “O Allah’s Messenger! Give it
to Abu Bakr who is sitting by your side.” But the Prophet (ﷺ) gave it to the bedouin, who was to his right
and said, “You should start with the one on your right side.”