Quran

This verse is a sound evidence for appointing an Imam or a Caliph (a Ruler) who is obeyed so he can unite the people and implement the laws. This obligatory duty (appointing a Ruler) is agreed upon unanimously among the scholars and the Muslim nation. Al-Qurtubi: 1/395.
Question: For the Muslim nation to be without a Ruler is considered a grave sin due to the resulting chaos and corruptions. Explain.

These two reasons, causing corruption and shedding blood, mentioned by the angels, are the same two reasons for which Allah ordained legal retribution for the Children of Israel.
Ibn Taimyah 1/192.
Question: What are the two reasons that if spread will lead to the destruction of nations?

The angels' statement was not an objection to Allah, nor was it an envy of the Children of Adam, but rather it was a question of inquiry of the wisdom behind that. Ibn Kathir: 1/67.
Question: Allah censured Iblis for his question but did not blame the angels for their question. Why?

(Will You place upon it one who causes corruption therein) by committing sin, (and sheds blood) although this is included in the meaning of the previous general statement (causes corruption); nevertheless, it is mentioned here in order to highlight the seriousness of killing. Al-Saadi: 48.
Question: Why is shedding blood specified even though it is included in causing corruption?

It is obligatory for someone who is asked about something he does not know to say: "Allah knows best, I do not know," following the example of the angels, Prophets, and virtuous scholars. The Prophet (r) stated that with the death of scholars, knowledge will be taken away, leaving ignorant people who will be asked for "fatwas" and they will issue "fatwas" according to their own opinions, so they will go astray and lead others astray. Al-Qurtubi: 1/425.
Question: What do we learn from the angels saying: "Glory be to You! We have no knowledge except what You have taught us"?

The prohibition against approaching the tree implies the prohibition against eating from it in the first instance. Forbidding the approach is an example of a principle in Fiqh called: "Blocking the means." Ibn Juzay: 1/62.
Question: What is the best way to avoid committing sins?

Allah's mercy precedes His punishment; He shows His mercy toward His servant in the midst of His wrath, just as He made the descending of Adam to earth a reason for his ascension, and Adam's remoteness a cause for his closeness to Him. Glory be to Him, the Forgiver, how honorable He is, and the Merciful, how great He is. Al-Alusi: 1/238.
Question: After reading the story of Adam (u), we should not despair of Allah's mercy. Explain.