Sahih al-Bukhari, Hadith 3888 ⓘ

Narrated Ibn `Abbas: Regarding the Statement of Allah" "And We granted the vision (Ascension to the heavens) which We made you see (as an actual eye witness) was only made as a trial for the people." (17.60) Ibn `Abbas added: The sights which Allah's Messenger was shown on the Night Journey when he was taken to Bait-ulMaqdis (i.e. Jerusalem) were actual sights, (not dreams). And the Cursed Tree (mentioned) in the Qur'an is the tree of Zaqqum (itself).

حَدَّثَنَا الْحُمَيْدِيُّ، حَدَّثَنَا سُفْيَانُ، حَدَّثَنَا عَمْرٌو، عَنْ عِكْرِمَةَ، عَنِ ابْنِ عَبَّاسٍ ـ رضى الله عنهما ـ فِي قَوْلِهِ تَعَالَى ‏{‏وَمَا جَعَلْنَا الرُّؤْيَا الَّتِي أَرَيْنَاكَ إِلاَّ فِتْنَةً لِلنَّاسِ‏}‏ قَالَ هِيَ رُؤْيَا عَيْنٍ، أُرِيَهَا رَسُولُ اللَّهِ صلى الله عليه وسلم لَيْلَةَ أُسْرِيَ بِهِ إِلَى بَيْتِ الْمَقْدِسِ‏.‏ قَالَ وَالشَّجَرَةَ الْمَلْعُونَةَ فِي الْقُرْآنِ قَالَ هِيَ شَجَرَةُ الزَّقُّومِ‏.‏