Tafsir of Ash-Shura 42:39

"And those who, when tyranny strikes them, they defend themselves."

It means that they limit their retaliation to what God has permitted for them, and they do not transgress.

It is narrated from al-Nakha‘i that whenever he recited this verse, he would say: "They used to dislike humiliating themselves, lest the wicked be emboldened against them."

If you ask: Are they praised for retaliating?

I say: Yes. Because whoever takes their right without transgressing the limits of God—and without exceeding the bounds in killing if they are a blood-avenger, or by responding to a fool in defense of their honor and to deter him—is obedient. And every obedient person is praiseworthy.

"And the retribution for an evil act is an evil one like it; but whoever pardons and makes reconciliation, his reward is [due] from Allah. Indeed, He does not like the wrongdoers."