It is narrated from Sayyiduna Sahl bin Sa'd al-Sa'idi (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Paradise has a gate called al-Rayyan, through which those who fast will be called. Whoever of those who fast enters through it will never be thirsty."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5733