Sahih Bukhari

Narrated Sahl bin Sa`d:Once a tumbler (full of milk or water) was brought to Allah's Messenger (ﷺ) 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 ! Do you allow me to give (the drink) to the elder people (first)?"" The boy said, ""I will not prefer anybody to have my share from you, O Allah's Apostle!"" So, he gave it to the boy