The one on the right should drink first

Narrated Anas bin Malik:

Milk mixed with water was brought to Allah's Apostle while a bedouin was on his right and Abu Bakr was on his left. He drank (of it) and then gave (it) to the bedouin and said, 'The right" "The right (first)."

حَدَّثَنَا إِسْمَاعِيلُ، قَالَ حَدَّثَنِي مَالِكٌ، عَنِ ابْنِ شِهَابٍ، عَنْ أَنَسِ بْنِ مَالِكٍ ـ رضى الله عنه ـ أَنَّ رَسُولَ اللَّهِ ﷺ أُتِيَ بِلَبَنٍ قَدْ شِيبَ بِمَاءٍ، وَعَنْ يَمِينِهِ أَعْرَابِيٌّ وَعَنْ شِمَالِهِ أَبُو بَكْرٍ، فَشَرِبَ، ثُمَّ أَعْطَى الأَعْرَابِيَّ، وَقَالَ " الأَيْمَنَ الأَيْمَنَ ".