﴾نَكَالًا﴿ “a severe punishment”, and this punishment is the most severe punishment to afflict them as it came after all that have been witnessed of the disobedience of the children of Israel, the stages that they fell into and every event that they had gone through. And this punishment will be for whoever that does as they did of disobedience and it is a warning to those with taqwa (fear of God).

النٌكول  : It is to go back or return. This means so that you will repent and return from this crime and you will not go back to it again.