Surah An-Nisa — Ayah 40 (4:40)
إِنَّ ٱللَّهَ لَا يَظۡلِمُ مِثۡقَالَ ذَرَّةٖۖ وَإِن تَكُ حَسَنَةٗ يُضَٰعِفۡهَا وَيُؤۡتِ مِن لَّدُنۡهُ أَجۡرًا عَظِيمٗا ٤٠
English translation (Saheeh International)
Indeed, Allāh does not do injustice, [even] as much as an atom's weight; while if there is a good deed, He multiplies it and gives from Himself a great reward.
Brief commentary
Allah is Just and does not wrong His creatures in any way. He does not lessen the good they do by the weight of even a tiny particle or dust, and He does not add to their disobedience in any way. Even if only an atom’s worth of good is done, He multiplies the reward, from His grace, and through this increase He gives a great reward.