Qatadah said: When this verse was revealed, Abu Jahl came with dates and butter, and said: "Eat (tazaqqamu), for we know the Zaqqum (bitter tree) to be nothing but this." Then Allah revealed: "It is a tree that emerges from the root of Hellfire."
Yahya said: It has reached me that it is in the sixth gate, and that it produces flames of fire just as a tree produces the coolness of water. Therefore, the people of the Fire—I mean those who are above it—must descend to it to eat from it.
قَالَ قَتَادَةُ: لَمَّا نَزَلَتْ هَذِهِ الْآيَة، جَاءَ أَبُو جهل بِتَمْر وزبد، وَقَالَ: تزقَّموا فَمَا نعلم الزقوم إِلَّا هَذَا، فَأنْزل اللَّه ﴿إِنَّهَا شَجَرَةٌ تَخْرُجُ فِي أَصْلِ الْجَحِيم﴾.
قَالَ يحيى: [بَلغنِي] أَنَّهَا فِي الْبَاب السَّادِس، وَأَنَّهَا تَجِيء بلهب النَّار؛ كَمَا تَجِيء الشَّجَرَة بِبرد المَاء، فَلَا بُد لأهل النَّار من أَن ينحدروا إِلَيْهَا، أَعنِي: من كَانَ فَوْقهَا؛ فيأكلوا مِنْهَا.