كتاب الأشربة
36  
The Book of Drinks
(17)
Chapter: It is recommended to pass water and milk etc., to the right of the one who drinks first
(17)
باب اسْتِحْبَابِ إِدَارَةِ الْمَاءِ وَاللَّبَنِ وَنَحْوِهِمَا عَنْ يَمِينِ الْمُبْتَدِئِ ‏‏
Sahih Muslim 2030 a

Sahl b. Sa'd Sa'idi reported that Allah's Messenger (ﷺ) was given a drink, and he drank from that, and there was on his right side a boy. and on his left some old men. He said to the boy:

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.
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، عَنْ مَالِكِ بْنِ أَنَسٍ، فِيمَا قُرِئَ عَلَيْهِ عَنْ أَبِي حَازِمٍ، عَنْ سَهْلِ بْنِ سَعْدٍ السَّاعِدِيِّ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم أُتِيَ بِشَرَابٍ فَشَرِبَ مِنْهُ وَعَنْ يَمِينِهِ غُلاَمٌ وَعَنْ يَسَارِهِ أَشْيَاخٌ فَقَالَ لِلْغُلاَمِ ‏"‏ أَتَأْذَنُ لِي أَنْ أُعْطِيَ هَؤُلاَءِ ‏"‏ ‏.‏ فَقَالَ الْغُلاَمُ لاَ ‏.‏ وَاللَّهِ لاَ أُوثِرُ بِنَصِيبِي مِنْكَ أَحَدًا ‏"‏ ‏.‏ قَالَ فَتَلَّهُ رَسُولُ اللَّهِ صلى الله عليه وسلم فِي يَدِهِ ‏.‏
Reference : Sahih Muslim 2030a
In-book reference : Book 36, Hadith 166
USC-MSA web (English) reference : Book 23, Hadith 5035
  (deprecated numbering scheme)