فَأَعْرَضُوا فَأَرْسَلْنَا عَلَيْهِمْ سَيْلَ الْعَرِمِ وَبَدَّلْنَاهُمْ بِجَنَّتَيْهِمْ جَنَّتَيْنِ ذَوَاتَيْ أُكُلٍ خَمْطٍ وَأَثْلٍ وَشَيْءٍ مِنْ سِدْرٍ قَلِيلٍ ﴿۱۶﴾ ذَلِكَ جَزَيْنَاهُمْ بِمَا كَفَرُوا وَهَلْ نُجَازِي إِلَّا الْكَفُورَ ﴿۱۷﴾

﴾16﴿ Fa a'radoo fa-arsalnaa 'alaihim Sailal 'Arimi wa baddalnaahum bijannataihim jannataini zawaatai ukulin khamtinw wa aslinw wa shai'im min sidrin qaleel
﴾17﴿ Zaalika jazainaahum bimaa kafaroo wa hal nujaazeee illal kafoor

﴾16﴿ But they turned away (from monotheism), so We sent upon them the flood of the dam and replaced their two gardens with others bearing bitter fruit, tamarisks, and a few lote trees
﴾17﴿ This was their recompense for their disbelief, and We do not punish in this way except those who are extremely ungrateful

[16] This passage mentions the reason for the punishment and the details of it:
(Fa a‘raḍū) — So they turned away — this is the reason for the punishment. Some narrations say that twelve prophets were sent to them, who called them to monotheism, but they turned away from it.
(Fa arsalnā ‘alayhim sayla al-‘arim) — So We sent upon them the flood of al-‘Arim — this is the description of the punishment. They had built a massive dam that collected rainwater or river water, and from it they directed canals and irrigation streams. The dam was called “arim.”
A hole formed in the dam (wall), it broke, and the water flooded their orchards and buildings. Since this was a divine punishment, the water carried poisonous elements that ruined the gardens. The fruits lost their sweetness and became tasteless.
(Ukulin khamṭin) — Al-Mubarrad says khamṭ refers to fruit that becomes so unappetizing no one desires it.
Abū ‘Ubayd says khamṭ refers to any bitter, thorny tree whose fruit is inedible.
(Wa athlin) — This refers to a type of tamarisk tree, which has no fruit and whose wood and shade are of no benefit.
(Sidr qalīl) — There are two kinds of sidr trees: one is bēr (jujube), which has bitter fruit, and the other is kahūr, which is very thorny and bears either no fruit or useless fruit and grows in deserts. The latter type is what is meant here.
[17] In this commentary, (fa a‘raḍū) means that their turning away was an act of disbelief.
(Wa hal nujāzī illā al-kafūr) — In this, the intended meaning of rewarding is complete uprooting (i.e., total destruction), as happened to the people of Saba. This kind of punishment is specific to disbelievers.
A second interpretation is that mujāzāh here means complete retribution—that not even a single sin is forgiven, and every sin is punished. This, too, is specific to disbelievers, because some of the sins of the believers are either forgiven through their acts of worship or simply by the grace of Allah, and they are not punished for every sin.