إِنَّ ٱلَّذِينَ ءَامَنُوا۟ وَعَمِلُوا۟ ٱلصَّـٰلِحَـٰتِ إِنَّا لَا نُضِيعُ أَجْرَ مَنْ أَحْسَنَ عَمَلًا
Innal lazeena aamanoo wa 'amilus saalihaati innaa laa nudee'u ajra man ahsana 'amalaa
Zaprawdę, ci, którzy uwierzą i którzy będą czynić dobre dzieła... - My na pewno nie pozwolimy, by przepadła nagroda temu, kto czynił dobro!
As for those who believe and do righteous deeds — indeed, we do not let the reward of anyone who does good go to waste.
Arabic opens this line with a subject and then never gives it a predicate: a fresh sentence starts where the completion should be, so the promise widens from those particular believers to anyone at all who acts well. Ahsana 'amalan comes back here from 18:7, where the adornment of the earth was set as a test of who would act best. The terms of the test return as the thing guaranteed against loss.