Surah 37. As-Saffat, Ayah 62

According to the lexicographers, the noun zaqqum (which occurs, apart from the present instance, in 44:43 and in 56:52 as well) denotes any "deadly food"; hence, the expression shajarat az-zaqqukm, a symbol of hell, may be appropriately rendered as "the tree of deadly fruit" (undoubtedly identical with "the tree cursed in this Qur'an", mentioned in 17:60 ), symbolizing the fact that the otherworldly sufferings which the Qur'an describes as "hell" are but the fruit - i.e., organic consequence - of one's evil deeds done on earth.

 The pagans of Mecca used to make fun of the Prophet (ﷺ) when he warned them of this tree. They asked, “How can a tree grow in Hell?” So Allah revealed this verse in response.

Cf. xvii. 60, n. 2250. This bitter tree of Hell is in contrast with the beautiful Garden of heaven with its delicious fruits.