Quran

Meaning: Allah states that on the Day of Resurrection, He will rebuke the idolators before all creation. He will ask the angels whom the idolators used to worship: (Was it you that they used to worship). Ibn Kathir: 3/520.
Question: What is the wisdom behind asking the angels about the worship of the idolators?

The testimony to nullify all deities besides Allah will be limited to the angels, since nullifying the deity of the angels will surely nullify that of everything else below them. This testimony will be the most important part of the Last Day's gathering. Ibn Ashur: 22/222.
Question: What is the benefit of limiting the testimony against the idolators to the angels on the Day of Resurrection?

Meaning: We have given the past nations power, blessings, and longevity (yet they rejected My messengers; how severe was My response), My reproach and destruction, so let these idolators be warned of the fate of past nations. Al-Baghawi: 3/611.
Question: What is the point of mentioning the fate of nations before Muhammad's (ﷺ) Ummah?

Meaning: That you should contemplate the matter of Muhammad (ﷺ) with sincerity to Allah, without leaning to desires or whims. (Stand up), not on your feet, rather, take the matter seriously. Ibn Juzay: 2/209.
Question: When is standing up in a matter for Allah considered sincere? When is it considered false?

(Then reflect): Have you known him to be a liar, insane, or corrupt; did he seek to learn magic from someone, did he learn tales and read the books, did he have a greed for your money, or can you produce one Surah the like of what he brought you? If you ascertain his truthfulness, after this reflection, then why are you stubborn!? (It is yours), you be my witness that this reward is yours. Al-Qurtubi: 17/330.
Question: What kind of reflection they are asked to do? Based on that, how can we know the Truth from falsehood?

There is also another matter that discourages people from following the one who calls them to the truth, which is the fear that he may take the wealth of those who respond to him and take it as payment for his call. Hence Allah explained that His Messenger (ﷺ) was far above doing such a thing, as He said: (Say, "If I had ever asked you for a reward, it is yours") for your following the truth. Al-Saadi: 683.
Question: In this verse, Allah describes a sign of the truthfulness of preachers. What is it?

Among Allah's Attributes, (the All-Knower of the unseen) is singled out for mention to indicate that He is aware of the intentions, and the Prophet (ﷺ) knows that, and therefore, he would never dare to falsely claim that Allah had sent him to you. Ibn Ashur: 22/238.
Question: In this verse, Allah's Attribute, (the All-Knower of the unseen) is singled out for mention. Why?