Much Of the Qur'an Relates the Story Of Musa And His People
Question :
Why does much of the Qur'an deal with the Children of Israel, and why do most chapters mention Musa?
Answer:
Musa is often mentioned because he is one of the five major Messengers, who are called "Ulul-'Azim." Moreover, Allah Almighty spoke directly to Musa and blessed him with many different miracles, one of which was in the way Fir'awn, His enemy, was destroyed. And despite being shown so many miracles, despite being blessed, the children of Israel disbelieved in Muhammad, even though they recognized him when he came, just as one of them was able to recognize his own children. The Qur'an reproaches them, because they knew but did not apply, because they were cognizant of the truth but refused to accept it for these reasons, they are mentioned often in the Qur'an.
Source:
Ibn Jibreen
Fatawa Islamiyah, Vol. 7 Page 47