Al-Lu'lu Wal-Marjan 1319 — The Book of Drinks (Al-Ashriba)

Sahl bin Sa`d Narrated from:

A tumbler (full of milk or water) was brought to the Prophet صلى الله عليه وسلم who drank from it, while on his right side there was sitting a boy who was the youngest of those who were present, and on his left side there were old men. The Prophet ﷺ asked, "O boy, will you allow me to give it (i.e. the rest of the drink) to the old men?" The boy said, "O Allâh's Messenger! I will not give preference to anyone over me to drink the rest of it from which you have drunk." So, the Prophet ﷺ gave it to him. ( Sahîh Al-Bukhârî, Hadîth No. 541, Vol. 3)