كتاب الجنة وصفة نعيمها وأهلها
53  
The Book of Paradise, its Description, its Bounties and its Inhabitants
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Chapter: In Paradise There Is A Tree In Whose Shade A Rider Could Travel For One Hundred Years And Still Not Cross It
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باب إِنَّ فِي الْجَنَّةِ شَجَرَةً يَسِيرُ الرَّاكِبُ فِي ظِلِّهَا مِائَةَ عَامٍ لاَ يَقْطَعُهَا ‏‏
Sahih Muslim 2827, 2828

Sahl b. Sa'd reported Allah's Messenger (ﷺ) as saying:

In Paradise, there is a tree under the shadow of which a rider can travel for a hundred years without covering (the distance) completely. This hadith has also been transmitted on the authority of Abu Sa'id al-Khudri that Allah's Apostle (ﷺ) is reported to have said: In Paradise, there is a tree under the shadow of which a rider of a fine and swift-footed horse would travel for a hundred years without covering the distance completely. There would be the pleasure of Allah for the inmates of Paradise and He would never be annoyed with them.
حَدَّثَنَا إِسْحَاقُ بْنُ إِبْرَاهِيمَ الْحَنْظَلِيُّ، أَخْبَرَنَا الْمَخْزُومِيُّ، حَدَّثَنَا وُهَيْبٌ، عَنْ أَبِي، حَازِمٍ عَنْ سَهْلِ بْنِ سَعْدٍ، عَنْ رَسُولِ اللَّهِ صلى الله عليه وسلم قَالَ ‏"‏ إِنَّ فِي الْجَنَّةِ لَشَجَرَةً يَسِيرُ الرَّاكِبُ فِي ظِلِّهَا مِائَةَ عَامٍ لاَ يَقْطَعُهَا ‏"‏ ‏.‏

قَالَ أَبُو حَازِمٍ فَحَدَّثْتُ بِهِ النُّعْمَانَ بْنَ أَبِي عَيَّاشٍ الزُّرَقِيَّ، فَقَالَ حَدَّثَنِي أَبُو سَعِيدٍ الْخُدْرِيُّ عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏"‏ إِنَّ فِي الْجَنَّةِ شَجَرَةً يَسِيرُ الرَّاكِبُ الْجَوَادَ الْمُضَمَّرَ السَّرِيعَ مِائَةَ عَامٍ مَا يَقْطَعُهَا ‏"‏ ‏.‏

Reference : Sahih Muslim 2827, 2828
In-book reference : Book 53, Hadith 9
USC-MSA web (English) reference : Book 40, Hadith 6786
  (deprecated numbering scheme)