Tafsir Ibn-Kathir:
( فَإِن تَوَلَّوْاْ But if they turn away), from the glorious, pure, perfect and encompassing Law that you -- O Muhammad -- brought them,
(فَقُلْ حَسْبِىَ اللَّهُ لا إِلَـهَ إِلاَّ هُوَ then say: "Allah is sufficient for me. There is no God but He,) Allah is sufficient for me, there is no deity worthy of worship except Him, and in Him I put my trust.
Similarly, Allah said, ((He alone is) the Lord of the east and the west; there is no God but He. So take Him alone as a guardian.) [73:9].
Allah said next, (Verily, there has come unto you a Messenger from among yourselves ...) [9:128]'' until the end of the Surah It is recorded in the Sahih that Zayd bin Thabit said, "I found the last Ayah in Surah Bara'ah with Khuzaymah bin Thabit.'' This is the end of Surah Bara'ah, all praise is due to Allah.
(وَهُوَ رَبُّ الْعَرْشِ الْعَظِيمِ and He is the Lord of the Mighty Throne) He is the King and Creator of all things, and He is the Lord of the Mighty Throne (`Arsh), which is above all creation; all that is in and between the heavens and earths is under the Throne (`Arsh) and subservient to Allah's power. His knowledge encompasses all things, and His decision will certainly come to pass over all matters. He is the guardian of all things.
Yusuf Ali Explanation:
But if the Message is rejected, he still proclaims the burning Faith of his heart, which is unquenchable. Allah is sufficient to all. To trust Him is to find the accomplishment of all spiritual desire. His grandeur is figured by a lofty Throne, supreme in glory! Thus, have we been led, through a notable incident in Al-Mustafa's earthly career, to truths of the highest spiritual import.
Explanation Qur'an Wiki:
The sūrah addresses the Prophet, showing him what attitude to take when people turn away from him and his message. It points to the source of power which gives him all the protection he needs. To Him belong all power, dominion, greatness and honour. His support is sufficient for everyone who seeks His patronage.
The sūrah which concentrates mainly on fighting and striving for God’s cause is thus concluded with the directive to rely on God alone, trust Him and seek His powerful support. After all “He is the Lord of the Mighty Throne.”
This sūrah outlines the final rulings on the permanent relations between the Muslim community and the outside world, as explained in our commentary on its various passages. Hence, we have to refer to its latest statements since these represent the final say on these relations. These statements must not be restricted or narrowed down in their applicability on the basis of earlier statements and rulings, which we described as provisional. In doing so, we have relied on the chronological order of the revelation of these verses and statements, and on the progress of the Islamic movement at the time of the Prophet, as well as the events marking that progress.
We have also been guided by our understanding of the nature of the Islamic message and its method of action which we have explained in our presentation of the sūrah and our commentary on its verses. This method of action is only understood by those who deal with this faith of Islam as a movement striving to establish itself in human life. As we have explained, the goal of that striving is to liberate mankind from submission to others so that they submit to God alone.
There is a wide gap between an understanding based on active striving and one based on academic study which is bound to ignore action. The first type of understanding looks at Islam as it conducts its direct confrontation with the system of jāhiliyyah, taking one step after another and moving from one stage to the next. It also looks at it as it proclaims its legislation to deal with the changing situation in its confrontation.
Moreover, these final laws and verdicts outlined in this last sūrah were actually revealed when the general situation of the Muslim community and the world around it required such legislation. Prior to that, when the situation required different rulings, these were given in earlier sūrahs to serve as provisional rulings.
When a new Muslim community emerges again and starts to strive for the establishment of this faith in human life, it may be appropriate for this community to apply the provisional rulings, provided that it remains well aware that these are only provisional. It should also be aware that it must strive to reach the stage when only the final rulings govern its relations with the world around it. God will certainly help that community and guide it on its way.
Now that is the messenger. This word is not that of the messenger, but the word of Allah. The Surah began and ended in the same place. Whoever turned away from this message has nothing to do with Allah and his messenger ﷺ. He, the Prophet Muhammad, is being told that if people turn away then you, who love them so much, tell them " Allah is enough for me."
Basically this is Prophet ﷺ declaring baraa from his own people if they turn away. This is at the end. In the beginning it was about disassociating from the people who do shirk. Now it is those who abandon the Prophet’s mission, those who stayed behind the messenger ﷺ. This is such a powerful ending. Allah (swt) challenges the Muslims.
If this Surah can be summarized, one of its main concluding themes is loyalty to the mission of Allah’s messenger ﷺ We as people have to feel a sense of loyalty that he ﷺ was on a mission and that mission is not over. Especially the immediate aspects of that mission if you look: Prophet ﷺ had already prepared a battalion to take over the Persians before he p assed. When he passed, that bat talion wasn’t cancelled. The Prophet ﷺ may not be with us. But his mission is. The chain of commanders was already set in place. Their loyalty was on to that. The hardest day on Ummah was the day of passing of Prophet ﷺ.
Aboobacker Siddeq (ra) says: “Whoever used to worship Mohammed, he ﷺ is dead. Allah is living He doesn’t die. And Allah’s word doesn’t die. Hence, the Prophet’s mission never dies.” The word of Allah keeps the mission of Allah going; t he mission that was charged to the messenger ﷺ.