Allah, the Exalted, says,

فَلاَ تَكُ فِى مِرْيَةٍ مِّمَّا يَعْبُدُ هَـؤُلاءِ

(So be not in doubt as to what these people worship.) This refers to the polytheists. Verily, what they are doing is falsehood, ignorance and misguidance. Verily, they are only worshipping what their fathers worshipped before. This means that they have no support for their Shirk. They are only mimicking their fathers in ignorance. Therefore, Allah will give them due recompense for that and He will punish them with a punishment the likes of which none can give besides Him. If they did any good deeds, then Allah will reward them for those good works in this life, before the life of the Hereafter. Concerning Allah's statement,

وَإِنَّا لَمُوَفُّوهُمْ نَصِيبَهُمْ غَيْرَ مَنقُوصٍ

(And verily, We shall repay them in full their portion without diminution.) `Abdur-Rahman bin Zayd bin Aslam said, "We will pay them in full their portion of punishment without diminution." Then, Allah mentions that He gave Musa the Book, but the people differed concerning it. Some believed in it and some disbelieved in it. Therefore, you, Muhammad, have an example in the Prophets who came before you. So do not grieve or be upset by their denial of you.

وَلَوْلاَ كَلِمَةٌ سَبَقَتْ مِن رَّبِّكَ لَقُضِيَ بَيْنَهُمْ

(and had it not been for a Word Kalimah that had gone forth before from your Lord, the case would have been judged between them,) Ibn Jarir said, "If it were not that the punishment had already been delayed until an appointed time, then Allah would have decided the matter between you now. The word Kalimah carries the meaning that Allah will not punish anyone until the proof has been established against him and a Messenger has been sent to him." This is similar to Allah's statement,

وَمَا كُنَّا مُعَذِّبِينَ حَتَّى نَبْعَثَ رَسُولاً

(And We never punish until We have sent a Messenger (to give warning).) 17:15 For verily, Allah says in another verse,

وَلَوْلاَ كَلِمَةٌ سَبَقَتْ مِن رَّبِّكَ لَكَانَ لِزَاماً وَأَجَلٌ مُّسَمًّى فَاصْبِرْ عَلَى مَا يَقُولُونَ

(And had it not been for a Word that went forth before from your Lord, and a term determined, (their punishment) must necessarily have come (in this world). So bear patiently what they say.)20:129-130 Then, Allah informs that He will gather the early generations and the later generations from all of the nations. He will then reward them based upon their deeds. If they did good deeds, their reward will be good, and if they did evil deeds, their reward will be bad. Allah says,

وَإِنَّ كُـلاًّ لَّمَّا لَيُوَفِّيَنَّهُمْ رَبُّكَ أَعْمَالَهُمْ إِنَّهُ بِمَا يَعْمَلُونَ خَبِيرٌ

(And verily, to each of them your Lord will repay their works in full. Surely, He is All-Aware of what they do.) This means that He is All-Knower of all of their deeds. This includes their honorable deeds and their despicable deeds, their small deeds and their great deeds. There are many different modes of recitation for this verse, yet all of their meanings agree with what we have mentioned. This is similar to Allah's statement,

وَإِن كُلٌّ لَّمَّا جَمِيعٌ لَّدَيْنَا مُحْضَرُونَ

(And surely, all - everyone of them will be brought before Us.)36:32