Sahih al-Bukhari, Book 59, Hadith 62 (In-Book) ⓘ
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."
حَدَّثَنَا رَوْحُ بْنُ عَبْدِ الْمُؤْمِنِ، حَدَّثَنَا يَزِيدُ بْنُ زُرَيْعٍ، حَدَّثَنَا سَعِيدٌ، عَنْ قَتَادَةَ، حَدَّثَنَا أَنَسُ بْنُ مَالِكٍ ـ رضى الله عنه ـ عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " إِنَّ فِي الْجَنَّةِ لَشَجَرَةً يَسِيرُ الرَّاكِبُ فِي ظِلِّهَا مِائَةَ عَامٍ لاَ يَقْطَعُهَا " .
also referenced under: Hadith 3251 (DarusSalam) & Volume 4, Book 54, Hadith 474 (USC-MSA)