Tafsir of Al Imran 3:120

(If a good thing touches you) O believers, (a good thing) meaning a blessing from your Lord, such as harmony, unity of purpose, and victory over enemies, (it grieves them) that is, it saddens and enrages them. (And if an evil befalls you) that is, an affliction, such as the enemy striking you or discord arising among you, (they rejoice) that is, they exult (at it). In this, there is an indication that their enmity has reached the extremity of envy and gloating.

It is said that "touching" (al-mass) is a metaphor for "befalling" (al-isaba), and thus they are synonyms here. They have been treated as equivalent in other places, such as His saying, Exalted is He: "If good befalls you, it grieves them, and if a disaster befalls you..." and His saying, "When evil touches him, he is impatient; and when good touches him, he is stingy." The expression here using "touching" with "good" and "befalling" with "evil" is merely for stylistic variation.

Some scholars of verification said: The best and most appropriate interpretation in this context is that it serves to indicate the excessiveness of their joy and grief. Since "touching" is lesser than "befalling" (as is apparent), if the least amount of good reaching you grieves them, then a greater amount is even more so. And if they rejoice at the greatest of calamities—the likes of which cause the gloater to be pitied and the envier to soften—then other calamities are even more so. Thus, there is no hope for their reconciliation at all; how, then, could you take them as intimates?

It is not far-fetched to say that this is an indication that the good which reaches them, in relation to Allah’s grace toward them, is a small good, while the evil which reaches them, in relation to the abundant reward it meets with, is something great—a point that is not hidden.

(And if you are patient) regarding their harm, or regarding the obedience of Allah and the intensity of striving in His cause, (and fear Him) by avoiding what He has forbidden you, (their plot) that is, their guile—and the origin of "plot" (kayd) is hardship—(will not harm you at all).

Ibn Kathir, Nafi’, Abu ‘Amr, and Ya’qub read la yadurrukum with a kasra on the dad and a jussive ra’ as the response to the condition, derived from dara-yadirru (to harm). The damma on the ra’ in the famous reading is to follow the damma of the dad, as is the case in doubled imperative verbs whose medial letter is damma, such as mudd (extend). The jussive is implied. Others allowed the fatha in such instances for ease, or the kasra to facilitate the movement of the quiescent letter. It is also said that it is in the nominative case with an implied fa’, but this is an unnecessary affectation.

(At all) is in the accusative as an adverbial source, meaning: their plot will not harm you in any way, neither much nor little, through the blessing of patience and piety, for they are among the best of acts of obedience and the most noble of character traits. Whoever adorns himself with these is under the protection and safeguard of Allah, shielded from the harm of an enemy's plot. It is also said: "Their plot will not harm you" because He encompasses them, and you possess an abundant reward; if the plot fails, it is a worldly blessing, so you are not deprived of the ultimate good in either case. This, however, is far-fetched.

(Indeed, Allah is encompassing of what they do) of plotting. Al-Hasan and Abu Hatim read ta’malun (you do) with a ta’, addressing the believers, meaning: whatever you do of patience and piety, (He is encompassing) by His knowledge or by a meaning befitting His Majesty, so He will punish them for their actions or reward you for yours.