Quran

(And whoever opposes Allah, Allah is truly severe in punishment): Here, He limits the opposition to Allah only because opposing Him is an opposition to His Messenger. Al-Shawkani: 5/196.
Question: This verse limits the opposition to Allah only. Why?

So that the wealth bestowed by Allah does not become a perpetual distribution among the rich and powerful leaders, while the weak and poor are left out. During the times of ignorance [pre-Islam], the head of the tribe used to take one-fourth of the spoils of war for himself, hence, Allah allocated this to His Messenger to divide it as He commands. Al-Baghawi: 4/357.
Question: What is meant by (So that wealth should not circulate only among those of you who are rich)?

This verse ends with the command to obey the Messenger (ﷺ) to remove what may reside in the souls of some in the Muslim army from being deprived of the booties bestowed by Allah upon His Messenger (ﷺ) from the land of Bani Al-Nadheer. Ibn Ashur: 28/86.
Question: This verse ends with the command to obey the Messenger (ﷺ). Why?

Allah relates that they gave what they had for charity despite their need, and they did not resent what their brethren were given. Based on that, they were free of stinginess and envy, and that is why stinginess and envy are of the same type, because an envious person does not like the giving by some to others while a stingy person does not like giving out of his own wealth. Ibn Taimyah: 6/272.
Question: This verse mentions two great traits of the believers. What are they?

The preference of others over oneself applies to worldly gains, not to the times spent in doing righteous deeds, as being stingy with such times is a true success. Whoever does not preserve his time, people will leave him in ruin. Preserving one's time is protecting one's heart and his greatest asset is his life. This is indicated by Allah's command to race one another and compete against each other in doing righteous deeds, which is the opposite of preferring others to oneself. Ibn Al-Qayim: 3/146.
Question: When is preferring others to oneself considered a good thing? When is stinginess considers good?

This level of faith is higher than that of those whom Allah described in these verses, (And they give food, despite their love for it) [76:8], and, (And gives his wealth, in spite of love for it) [2:177]. These give charity despite their love for their wealth, however, they are not in need for it, nor it is necessary for them to keep. The former prefer others to themselves even though they are in need and have a necessity for what they spend in charity. Ibn Kathir: 4/338.
Question: Who is better: One who prefers others to himself, or one who gives charity despite his loves for it?

If a person is protected from his own covetousness, he will be at ease with the commands of Allah and His Messenger (ﷺ), and will comply with them obediently and willingly, with an open heart, and he will be at ease with refraining from what Allah forbids, even if it is dear to him and his heart longs for it. He will be at ease with spending his wealth in Allah's cause, seeking His pleasure. Thus, he will attain success and triumph. Al-Saadi: 851.
Question: Protection from the covetousness of one's soul is a reason for success. How?