Overall meaning : Allah Almighty states that the believers from amongst those to whom Muhammad, may Allah bless him and grant him peace, has been sent, as well the Jews, the Christians and the Sabaeans, all of them who followed the true religion before it was abrogated or before distortions and corruptions took place in it—all those of them who believe in Allah and the Last Day, do good deeds and are obedient to Allah will have their reward with their Lord, and they will have nothing whatsoever to fear in the hereafter, nor will they grieve for whatever they leave behind in the life of the world. Nonetheless, after the advent of Prophet Muhammad, may Allah bless him and grant him peace, the persons deserving such a reward are only those who believe him and follow his religion—Islam.
Then the Almighty reminds the Children of Israel of the time when He made a solemn covenant with them, whereby they pledged themselves to believe in Him and His messengers and to keep His commandments, and He raised the mountain high above them to frighten them into acknowledging what they had pledged to do and commanded them to hold firmly to the Torah and to read it and follow its teachings so that they might become righteous.
He then mentions that they had broken the covenant and turned away from it, and that had it not been for the grace of Allah who helped them to show sincere repentance, they would have surely been among the losers in this world and the hereafter.
You surely know, O Jews, those of you who violated the limits of Allah and disobeyed His commandments by breaking the Sabbath and fishing on Saturday when they were commanded not to, and so He turned them into apes, despised and contemptible. Allah made this punishment as a deterrent to those who were around those who had been transformed into apes and a lesson for the righteous and God-fearing.