Al-Baqarah: 265
"And to strengthen their own souls"
It means to strengthen their souls by sacrificing wealth, which is the twin of the soul. Sacrificing it is the most difficult thing for the soul, more so than other arduous acts of worship or even faith itself. This is because when the soul is disciplined by being burdened and tasked with what it finds difficult, it becomes submissive and obedient to its master, and its greed in following its desires diminishes. Conversely, the opposite is true. Thus, spending wealth serves as a strengthening of the soul in faith and certainty.
It is also permissible that it means "confirming Islam and verifying the reward from the core of their own souls." This is because when a Muslim spends their wealth in the way of Allah, they know that their confirmation and belief in the reward stems from the core of their soul and the sincerity of their heart.
In the first interpretation, the min (from) is for partition (tab'id), similar to the saying: "He shook from his side" and "He moved from his energy."
In the second interpretation, it is for the beginning of the origin (ibtida' al-ghayah), as in the Almighty’s saying: "Out of envy from their own souls" (2:109).
It is also possible that the meaning is: "And to demonstrate to the believers that their souls are sincere in faith and devoted to it." This is supported by the reading of Mujahid: "And to make clear from their own souls."
If you ask: What is the meaning of partition here?
I say: Its meaning is that whoever sacrifices their wealth for the sake of Allah has strengthened part of their soul, and whoever sacrifices both their wealth and their soul together is the one who has strengthened the whole of it, as in: "And you strive in the way of Allah with your wealth and your souls" (As-Saff: 11).
"And the likeness of the spending of these people in its purity before Allah is like a garden"
A garden (jannah).
"On a high ground"
A raised place. It is specified because the trees there are purer and better in fruit.
"A heavy rain (wabil) strikes it"
Rain with large drops.
"So it brings forth its fruit"
Its produce.
"Double"
Twice what it would usually produce because of the heavy rain.
"And if a heavy rain does not strike it, then a light rain (tall)"
A rain with small drops suffices it because of the excellence of its soil.
Or, the likeness of their state before Allah is like the garden on the high ground, and their spending—whether much or little—is like the heavy rain and the light rain. Just as each of the two types of rain doubles the fruit of the garden, so too is their spending, whether much or little, provided it is done seeking the Face of Allah and with maximum effort; it is pure before Allah, increasing their proximity and the excellence of their state with Him.
Note: It was read as "kamathali habbatin" (like a grain), "bi-rabwatin" (on a high ground) with the three vowel marks, and "ukulaha" (its fruit) with two dammahs.
"Would one of you like to have a garden of palm trees and grapevines, underneath which rivers flow, in which he has every kind of fruit, while old age has struck him and he has weak offspring, and a whirlwind containing fire strikes it, so it is all burned? Thus does Allah make clear to you the verses that you might give thought." (266)