Sahih Bukhari Volume 4, Book 54, Hadith Number 475.

Narated By Abu Huraira : The Prophet said “There is a tree in Paradise (which is so big and huge that) a rider could travel in its shade for a hundred years. And if you wish, you can recite: ‘In shade long extended…’ (56. 30) and a place in Paradise equal to an arrow bow of one of you, is better than (the whole earth) on which the sun rises and sets.”