Tafsir of Luqman 31:23

"And whoever disbelieves, let not his disbelief grieve you..."

It has been recited as yaḥzunuka (grieve you) and yuḥzinuka (cause you grief), derived from ḥazana and aḥzana. The most widespread usage is aḥzanahu and yuḥzinuhu.

The meaning is: Do not let the disbelief of those who disbelieve, nor their plotting against Islam, concern you. For Allah, the Almighty and Exalted, will repel their plot back upon them, take vengeance upon them, and punish them for their deeds.

"Indeed, Allah is Knowing of what is within the breasts" He knows what is in the hearts of His servants, and He deals with them accordingly.

"We grant them enjoyment for a little while" In their worldly life.

"Then We will force them to a severe punishment" He likens compelling them into torment and overwhelming them with it to the state of one who is forced into something from which he cannot escape.

"Severity" (ghilẓ) is a metaphor borrowed from thick, dense physical objects. The intended meaning is intensity and heaviness upon the one being punished.

"And if you asked them, 'Who created the heavens and the earth?' they would surely say, 'Allah.' Say, '[All] praise is [due] to Allah'; but most of them do not know. To Allah belongs whatever is in the heavens and the earth. Indeed, Allah is the Free of need, the Praiseworthy. And if whatever trees upon the earth were pens and the sea [was] ink, replenished thereafter by seven [more] seas, the words of Allah would not be exhausted. Indeed, Allah is Exalted in Might and Wise."