Hadith: The Messenger of Allah (may Allah's peace and blessings be upon him) was brought milk mixed with water. A Bedouin was sitting on his right and Abu Bakr (may Allah be pleased with him) was sitting on his left. He drank then gave it to the Bedouin and said: The one on the right (first) then again the one on the right

عن أنس بن مالك رضي الله عنه أَنَّ رسولَ اللهِ صلى الله عليه وسلم أُتِيَ بِلَبَنٍ قد شِيبَ بماءٍ، وعن يمينهِ أَعْرَابِيٌّ، وعن يَسَارِه أبو بكرٍ رضي الله عنه فَشَرِبَ، ثم أَعْطَى الأَعْرَابِيَّ، وقال: «الأَيْمَنَ فَالأَيْمَنَ».
[صحيح] - [متفق عليه]

Anas ibn Mālik (may Allah be pleased with him) reported: The Messenger of Allah (may Allah's peace and blessings be upon him) was brought milk mixed with water. A Bedouin was sitting on his right and Abu Bakr (may Allah be pleased with him) was sitting on his left. He drank then gave it to the Bedouin and said: "The one on the right (first) then again the one on the right."
Sahih/Authentic. - [Al-Bukhari and Muslim]

Explanation

The Prophet (may Allah's peace and blessings be upon him) was brought milk mixed with water. On his right side there was a Bedouin and on his left side there was Abu Bakr. The Prophet (may Allah's peace and blessings be upon him) drank from the milk then gave it to the Bedouin, who took it and drank. Although Abu Bakr has more merit than the Bedouin, the Prophet (may Allah's peace and blessings be upon him) gave the Bedouin preference over him because he was on his right, then he said: "The one on the right then again the one on the right," meaning, start with the one on your right side then again the one on his right side and so on.