Sahih Bukhari Volume 8, Book 76, Hadith Number 581.

Narated By ‘Abdullah bin ‘Amr : The Prophet said, “My Lake-Fount is (so large that it takes) a month’s journey to cross it. Its water is whiter than milk, and its smell is nicer than musk (a kind of Perfume), and its drinking cups are (as numerous) as the (number of) stars of the sky; and whoever drinks from it, will never be thirsty.”