´Anas narrated that the Prophet said:` “Indeed in Paradise there is a tree under whose shade a rider can travel for one hundred years without stopping. Recite if you wish: And in shave extended. And water flowing constantly.”
Hadith Referenceسنن ترمذي / كتاب تفسير القرآن عن رسول الله صلى الله عليه وسلم / 3293
Narrated Anas bin Malik: The Prophet said, "There is a tree in Paradise (which is so big and huge that) if a rider travels in its shade for one hundred years, he would not be able to cross it."
Maulana Dawood Raz
Hadith Commentary: In Surah Al-Waqi’ah, Allah the Exalted has mentioned regarding the shade of Paradise: “And extended shade” (Al-Waqi’ah: 30), meaning that there, the shade of the trees will be spread far and wide. O Allah, grant all of us who value this book that shade of Paradise. It is as clear as daylight from the ahadith and verses that Paradise is the name of a tangible reality. Those who consider Paradise to be merely a matter of dreams and imagination are caught in a dangerous error. For such people with erroneous beliefs, if Paradise remains nothing more than a dream and something impossible to interpret, it is not surprising. Allahumma la taj‘alna minhum. Ameen.
Source: Sahih Bukhari: Commentary by Maulana Dawood Raz, Page: 3251