Riyad Us-Saliheen (Gardens of the Righteous)

Chapter 115
Excellence of Cupbearer drinking Last

773. Abu Qatadah (May Allah be pleased with him) reported: Messenger of Allah (PBUH) said, "He who serves others with drinking water should be the last to drink himself.''
[At-Tirmidhi].

Commentary: Referring to this Hadith, Imam An-Nawawi stresses the manner of serving food or drink and says that the distributor should have his share in the end.