Tafsir of Ash-Shura 42:43

{And whoever is patient} regarding injustice and harm, {and forgives}—meaning he does not seek retribution and entrusts his affair to Allah—

{that}—that action of his—{is indeed of the matters of determination.} The pronoun referring back to the subject (the ‘a’id) is omitted because it is understood, just as it is omitted in their saying: "The ghee is two manns for a dirham" (meaning: two manns of it).

It is narrated that a man insulted another in the gathering of al-Hasan (may Allah have mercy on him). The one being insulted suppressed his anger, sweating, and would wipe away the sweat. Then he stood up and recited this verse. Al-Hasan said: "By Allah, he has grasped it and understood it, while the ignorant have wasted it."

Scholars have said: Forgiveness is recommended. However, the matter may be reversed in certain circumstances, where refraining from forgiveness becomes recommended. This is when it is necessary to curb the increase of transgression and cut off the source of harm. There is evidence for this from the Prophet (peace and blessings of Allah be upon him):

(998) Zaynab spoke harshly to ‘A’ishah in his presence. He forbade her, but she did not stop. So he said to ‘A’ishah: "Go ahead and take your right (retaliate)."

{And whoever Allah sends astray, there is no protector for him after Him. And you will see the wrongdoers, when they see the punishment, saying, "Is there any way to return?"}