Overall meaning : And remind them, Muhammad, of the time when We informed the Jews of what He had decreed would happen to them—which has come to pass and will inevitably continue to happen—namely that He would continue to send others against them, until Resurrection Day, to afflict them with grievous torment. Surely, your Lord is swift in inflicting punishment on the unbelievers and sinners when they become deserving of it, yet He is All-Forgiving, All-Merciful.
The Almighty states that He dispersed the Children of Israel into communities throughout the earth, some of them righteous, and some of them otherwise; and He tried them with blessings and misfortunes so that they might return to Him in sincere obedience and repent of their sins. Then there came after them an evil generation who inherited the Torah from their ancestors and knew about the laws it contained, yet they ignored its instructions. They would take the unlawful, fleeting worldly gains and say, being self-deluded, 'Allah will forgive us.’ And if such unlawful worldly gains came their way once more, they would persist in their sins and take them again! Was a solemn covenant not made with them in the Torah whereby they bound themselves to say nothing about Allah except the truth, given that they had read it and studied its contents well? Surely, the great reward and bliss Allah has prepared in the hereafter for those who do what He commands and avoid what He forbids is far better than such paltry and transitory worldly gains. Will those who take such unlawful gains and act contrary to Allah’s commands in the Book, then, understand and use their intellect?
As for those who strictly observe Allah’s Book (the Qur’an), follow the instructions in it and duly perform the prescribed prayers, the Almighty points out, they will be among the righteous and good-doers, stating that He will by no means deny them their reward.