Do you permit me to give it to them (the old men), but that boy said: by God. I will not give preference at your hand over me in my share. He (the narrator) said that Allah's Messenger (ﷺ) then gave it in his hand.
Sahih Muslim Book 36, Hadith 166
← Previous Hadith Allah's Messenger (ﷺ) came to our house and he asked for a drink. We milked a goat for him and then mixed it (the milk) with the water of this well of mine. I gave it to Allah's Messenger (ﷺ) and he drank it, while Abu Bakr was on his left and 'Umar was in front of him, and a desert Arab was on his right. When Allah's Messenger (ﷺ) had finished the drink, Umar said: Allah's Messenger, here is Abu Bakr, give him to drink; but Allah's Messenger (ﷺ) gave it to the desert Arab and he left out Abu Bakr and Umar. And Allah's Messenger (ﷺ) said: Those on the right, those on the right, those on the right (deserve preference). Anas said: This is the Sunnah, this is the Sunnah, this is the Sunnah.

Sahih Muslim Book 36, Hadith 165 Next Hadith → This hadith is reported on the authority of Sahl b. Sa'd with a slight variation of wording.

Sahih Muslim Book 36, Hadith 167