Regarding: 'And We granted the vision (Ascension to the Heaven "Miraj") which We showed you (O Muhammad as an actual eye witness) but as a trial for mankind.' (17.60) It was an actual eyewitness which was shown to Messenger of Allah ﷺ during the night he was taken on a journey (through the heavens). And the cursed tree is the tree of Az-Zaqqum (a bitter pungent tree which grows at the bottom of Hell).

هِيَ رُؤْيَا عَيْنٍ أُرِيَهَا رَسُولُ اللَّهِ ﷺ لَيْلَةَ أُسْرِيَ بِهِ {وَالشَّجَرَةَ الْمَلْعُونَةَ} شَجَرَةُ الزَّقُّومِ

[AI] In His saying, "And We have not made the vision which We showed you except as a trial for the people." [Surah Al-Isra 60], He said, it is a vision of an eye that the Prophet ﷺ saw on the night of his ascension.

فِي قَوْلِهِ ﷻ {وَمَا جَعَلْنَا الرُّؤْيَا الَّتِي أَرَيْنَاكَ إِلا فِتْنَةً لِلنَّاسِ} [الإسراء 60] قَالَ هِيَ رُؤْيَا عَيْنٍ رَآهَا النَّبِيُّ ﷺ لَيْلَةَ أُسْرِيَ بِهِ

[AI] It translates to: "She has the Messenger of Allah, ﷺ , do not underestimate him."

لَهَا رَسُولُ اللهِ ﷺ لَا تُسَبِّخِي عَنْهُ

[AI] "It is the vision of an eye that I saw on the night of my ascension."

فِي قَوْلِهِ تَعَالَى {وَمَا جَعَلْنَا الرُّؤْيَا الَّتِي أَرَيْنَاكَ إِلَّا فِتْنَةً لِلنَّاسِ} [الإسراء 60] قَالَ «هِيَ رُؤْيَا عَيْنٍ رَأَى لَيْلَةَ أُسْرِيَ بِهِ»

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 ʿAbbas added: The sights which Messenger of Allah ﷺ 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) . (Using translation from Bukhārī 3888)

فِي قَوْلِهِ تَعَالَى {وَمَا جَعَلْنَا الرُّؤْيَا الَّتِي أَرَيْنَاكَ إِلَّا فِتْنَةً لِلنَّاسِ} قَالَ «هِيَ رُؤْيَا عَيْنٍ أُرِيَهَا رَسُولُ اللَّهِ ﷺ لَيْلَةَ أُسْرِيَ بِهِ»