﴿فَلِذَلِكَ فَادْعُ وَاسْتَقِمْ كَمَآ أُمِرْتَ وَلاَ تَتَّبِعْ أَهْوَآءَهُمْ وَقُلْ ءَامَنتُ بِمَآ أَنزَلَ اللَّهُ مِن كِتَـبٍ وَأُمِرْتُ لاًّعْدِلَ بَيْنَكُمُ اللَّهُ رَبُّنَا وَرَبُّكُمْ لَنَآ أَعْمَـلُنَا وَلَكُمْ أَعْمَـلُكُمْ لاَ حُجَّةَ بَيْنَنَا وَبَيْنَكُمُ اللَّهُ يَجْمَعُ بَيْنَنَا وَإِلَيْهِ الْمَصِيرُ ﴾
(15. So unto this then invite (people), and stand firm as you are commanded, and follow not their desires but say: “I believe in whatsoever Allah has sent down of the Book and I am commanded to do justice among you. Allah is our Lord and your Lord. For us our deeds and for you your deeds. There is no dispute between us and you. Allah will assemble us (all), and to Him is the final return.”)
(So unto this then invite (people),) means, `so call people to this which We have revealed to you and which We enjoined upon all the Prophets before you,’ the Prophets of major ways ﴿of Shari`ah﴾ that were followed, such as the Messengers of strong will, and others.
﴿وَاسْتَقِمْ كَمَآ أُمِرْتَ﴾
(and stand firm as you are commanded, ) means, `adhere firmly, you and those who follow you, to the worship of Allah as He has commanded you.’
﴿وَلاَ تَتَّبِعْ أَهْوَآءَهُمْ﴾
(and follow not their desires) means, the desires of the idolators, in the falsehoods that they have invented and fabricated by worshipping idols.
﴿وَقُلْ ءَامَنتُ بِمَآ أَنزَلَ اللَّهُ مِن كِتَـبٍ﴾
(but say: “I believe in whatsoever Allah has sent down of the Book…”) means, `I believe in all the Books that have been revealed from heaven to the Prophets; we do not differentiate between any of them.’
﴿وَأُمِرْتُ لاًّعْدِلَ بَيْنَكُمُ﴾
(and I am commanded to do justice among you.) means, when judging according to the commands of Allah.
﴿اللَّهُ رَبُّنَا وَرَبُّكُمْ﴾
(Allah is our Lord and your Lord.) means, `He is the One Who is to be worshipped, and there is no true God but He. We affirm this willingly, and even though you do not do so willingly, everyone in the universe prostrates to Him obediently and willingly.’
﴿لَنَآ أَعْمَـلُنَا وَلَكُمْ أَعْمَـلُكُمْ﴾
(For us our deeds and for you your deeds.) means, `we have nothing to do with you. ‘ This is like the Ayah:
﴿وَإِن كَذَّبُوكَ فَقُل لِّى عَمَلِى وَلَكُمْ عَمَلُكُمْ أَنتُمْ بَرِيئُونَ مِمَّآ أَعْمَلُ وَأَنَاْ بَرِىءٌ مِّمَّا تَعْمَلُونَ ﴾
(And if they deny you, say: “For me are my deeds and for you are your deeds! You are innocent of what I do, and I am innocent of what you do!”) (10:41)
﴿لاَ حُجَّةَ بَيْنَنَا وَبَيْنَكُمُ﴾
(There is no dispute between us and you.) Mujahid said, “This means, no argument.” As-Suddi said, “This was before Ayah of the sword was revealed.” This fits the context, because this Ayah was revealed in Makkah, and Ayah (22:39-40) was revealed after the Hijrah.
﴿اللَّهُ يَجْمَعُ بَيْنَنَا﴾
(Allah will assemble us (all),) means, on the Day of Resurrection. This is like the Ayah:
﴿قُلْ يَجْمَعُ بَيْنَنَا رَبُّنَا ثُمَّ يَفْتَحُ بَيْنَنَا بِالْحَقِّ وَهُوَ الْفَتَّاحُ الْعَلِيمُ ﴾
(Say: “Our Lord will assemble us all together, then He will judge between us with truth. And He is the Just Judge, the All-Knower of the true state of affairs.”) (34:26).
(and to Him is the final return.) means, the final return on the Day of Reckoning.
SOURCE: Tafsir Ibn Kathir