فَمَن يَعْمَلْ مِنَ الصَّالِحَاتِ وَهُوَ مُوْمِنٌSo whoever does righteous good deeds while he is a believer,meaning, his heart believes and his deeds are righteous. فَلَ كُفْرَانَ لِسَعْيِهِhis efforts will not be rejected.This is like the Ayah:إِنَّا لَا نُضِيعُ أَجْرَ مَنْ أَحْسَنَ عَمَلًcertainly We shall not make the reward of anyone who does his deeds in the most perfect manner to be lost. (18:30)which means, his efforts will not be wasted; they will be appreciated and not even a speck of dust's weight of injustice will be done.Allah says:وَإِنَّا لَهُ كَاتِبُونَVerily, We record it for him.means, all his deeds are recorded and nothing of them at all is lost