Once Allah's Messenger (ﷺ) visited us in this house of ours and asked for something to drink. We milked one
of our sheep and mixed it with water from this well of ours and gave it to him. Abu Bakr was sitting
on his left side and `Umar in front of him and a bedouin on his right side. When Allah's Messenger (ﷺ)
finished, `Umar said to Allah's Messenger (ﷺ) "Here is Abu Bakr." But Allah's Messenger (ﷺ) gave the remaining
milk to the bedouin and said twice, "The (persons on the) right side! So, start from the right side."
Anas added, "It is a Sunna (the Prophet's traditions)" and repeated it thrice.
Sahih al-Bukhari Book 51, Hadith 6