﴿ وَسْـَٔلْهُمْ عَنِ ٱلْقَرْيَةِ ٱلَّتِى كَانَتْ حَاضِرَةَ ٱلْبَحْرِ إِذْ يَعْدُونَ فِى ٱلسَّبْتِ إِذْ تَأْتِيهِمْ حِيتَانُهُمْ يَوْمَ سَبْتِهِمْ شُرَّعًۭا وَيَوْمَ لَا يَسْبِتُونَ ۙ لَا تَأْتِيهِمْ ۚ كَذَٰلِكَ نَبْلُوهُم بِمَا كَانُوا۟ يَفْسُقُونَ ﴾

“And ask them about that town which stood by the sea: how its people would profane the Sabbath whenever their fish came to them, breaking the water's surface, on a day on which they ought to have kept Sabbath -because they would not come to them on other than Sabbath-days! Thus did We try them by means of their [own] iniquitous doings.”

It is a sin to do anything which God has prohibited. But to perform a prohibited act by attempting to legalize it through some trick amounts to adding insult to injury. By violating the rule of the Sabbath, the Jews had committed a double sin. Such people must suffer divine retribution; that is, they are deprived of the bounties which God has set apart for human beings alone. In this world such people fall from the level of humanity to the level of the animals.