سُبْحَانَ ٱللَّٰهِ
Holy Qur'an
Al-Qur'an
Kids Qur'an
I.e., "thou art not the first of Our apostles, O Muhammad: We have sent thee to the people of thy time just as We sent Shu'ayb to the people of Madyan" (Ad-Dahhak, as quoted by Razi).
So they neglected the Commandments over time.
That is, there were many generations that passed between Moses and the holy Prophet. Yet he knew by inspiration of the events of those times. Even if he had lived then, he could not have known the events that took place among the Midianites, except by inspiration, as he did not dwell among them.
'Though thou wast not among the Midianites, Our inspiration has told thee of the momentous events that took place among them when Moses was with them. This is itself a Sign that should make thy people understand.'