This Ayah 3:79 means, it is not for a person whom Allah has given the Book, knowledge in the Law and prophethood to proclaim to the people, "Worship me instead of Allah," meaning, along with Allah. If this is not the right of a Prophet or a Messenger, then indeed, it is not the right of anyone else to issue such a claim.
This criticism refers to the ignorant rabbis, priests and teachers of misguidance, unlike the Messengers and their sincere knowledgeable followers who implement their knowledge; for they only command what Allah commands them, as their honorable Messengers conveyed to them. They also forbid what Allah forbade for them, by the words of His honorable Messengers. The Messengers, may Allah's peace and blessings be on all of them, are the emissaries between Allah and His creation, conveying Allah's Message and Trust. The messengers indeed fulfilled their mission, gave sincere advice to creation and conveyed the truth to them. Allah's statement,
(On the contrary (he would say), "Be you Rabbaniyyun, because you are teaching the Book, and you are studying it.") means, the Messenger recommends the people to be Rabbaniyyun. Ibn `Abbas, Abu Razin and several others said that Rabbaniyyun means, "Wise, learned, and forbearing." Ad-Dahhak commented concerning Allah's statement,
(because you are teaching the Book, and you are studying it.) "Whoever learns the Qur'an deserves to become a Faqih (learned)."
(and you are studying it), preserving its words.
Allah then said,
(Nor would he order you to take angels and Prophets for lords.) The Prophet does not command worshipping other than Allah, whether a sent Messenger or an angel.
(Would he order you to disbelieve after you have submitted to Allah's will) meaning, he would not do that, for whoever calls to worshipping other than Allah, will have called to Kufr. The Prophets only call to Iman which commands worshipping Allah Alone without partners. Allah said in other Ayat,
(And We did not send any Messenger before you (O Muhammad ) but We revealed to him (saying): "None has the right to be worshipped but I, so worship Me".) 21:25,
(And verily, We have sent among every Ummah a Messenger (proclaiming): "Worship Allah (Alone), and avoid Taghut (all false deities).") 16:36, and,
(And ask those of Our Messengers whom We sent before you: "Did We ever appoint gods to be worshipped besides the Most Gracious (Allah)") 43:45
Allah said concerning the angels,
(And if any of them should say: "Verily, I am a god besides Him (Allah)," such a one We should recompense with Hell. Thus We recompense the wrongdoers.) 21:29.