Then whoever turns his back after that, that is, after having known God's covenant with the prophets and the prophets' communication to him of what God has pledged to them, those they are, the ones who have departed from God's religion, and there is no other religion in reality on which to rely except that it be illusion.
Taking a Pledge From the Prophets to Believe in Our Prophet, Muhammad
Allah states that He took a pledge from every Prophet whom He sent from Adam until `Isa, that when Allah gives them the Book and the Hikmah, thus acquiring whatever high grades they deserve, then a Messenger came afterwards, they would believe in and support him. Even though Allah has given the Prophets the knowledge and the prophethood, this fact should not make them refrain from following and supporting the Prophet who comes after them. This is why Allah, the Most High, Most Honored, said
(They said: "We agree.'' He said: "Then bear witness; and I am with you among the witnesses.'' then whoever turns away after this,'') from fulfilling this pledge and covenant, c
فَأُوْلَـئِكَ هُمُ الْفَـسِقُونَ
(they are the rebellious.) `Ali bin Abi Talib and his cousin `Abdullah bin `Abbas said, "Allah never sent a Prophet but after taking his pledge that if Muhammad were sent in his lifetime, he would believe in and support him.'' Allah commanded each Prophet to take a pledge from his nation that if Muhammad were sent in their time, they would believe in and support him. Tawus, Al-Hasan Al-Basri and Qatadah said, "Allah took the pledge from the Prophets that they would believe in each other'', and this statement does not contradict what `Ali and Ibn `Abbas stated.
Therefore, Muhammad is the Final Prophet until the Day of Resurrection. He is the greatest Imam, who if he existed in any time period, deserves to be obeyed, rather than all other Prophets. This is why Muhammad led the Prophets in prayer during the night of Isra' when they gathered in Bayt Al-Maqdis (Jerusalem). He is the intercessor on the Day of Gathering, when the Lord comes to judge between His servants. This is Al-Maqam Al-Mahmud (the praised station) refer to 17:79 that only Muhammad deserves, a responsibility which the mighty Prophets and Messengers will decline to assume. However, Muhammad will carry the task of intercession, may Allah's peace and blessings be on him.
Maududi - Sayyid Abul Ala Maududi - Tafhim al-Qur'an
It implies this: "You people of the Book are bound by the Covenant of your own Prophets to believe in and help Muhammad (Allah's peace be upon him) for we entered into a compact with every Prophet to the effect that they (and their followers by implication) must help every Prophet sent by Us for the preaching and the establishment of the way of life for which they had been appointed. Therefore you should not have any prejudice against him, nor consider religion as your own monopoly; you should not oppose the Truth but come under the banner of anyone who raises it for this purpose.
It is interesting to note that according to Palmer (The Koran), "the Talmudic sources confirm that God assembled all past, present, and future Prophets on Mount Sinai and entered into the compact mentioned in the text."
In this connection it should also be clearly understood that this compact was taken from every Prophet before the advent of Hadrat Muhammad (Allah's peace be upon him); therefore every Prophet informed his followers about the Prophet coming after him and told them to follow him. But there is no mention in the Qur'an or in the Traditions that any such compact was taken from the Holy Prophet: nor did he inform his followers about the coming of any Prophet after him and believing in him. On the contrary, he categorically declared that he was the last in the line of Prophets.
This implies that the people of the Book were breaking their covenant with Allah by rejecting Prophet Muhammad (God's peace be upon him) and opposing his mission; they were disregarding that covenant which their Prophets had made with Allah. Hence they were perverted transgressors who had gone beyond the limits imposed by Allah.
Then whoever turns his back after that they are the wicked. This alludes to whoever abandons [the Prophet's] way sunna or wanders [away] from following his path Ṭarīqa after the appearance of [the Prophet's] evidence and the clarity of his miracle. They are those whose condition has become corrupted. They have become deserving of wrath because of their denial and the breaking of their attachment to the divine solicitude.