Tafsir of An-Nisa' 4:39

وماذا عليهم لو آمنوا بالله واليوم اﻻخر وأنفقوا مما رزقهم الله

And what loss have they if they had believed in Allah and in the Last Day, and they spend out of what Allah has given them for sustenance! This Ayah means, what harm would it cause them if they believe in Allah, go on the righteous path, replace showing off with sincerity, have faith in Allah, and await His promise in the Hereafter, for those who do good and spend what He has given them on what He likes and is pleased with. Allah's statement:

وكان الله بهم عليما

And Allah is Ever All-Knower of them. means, He has perfect knowledge of their intentions, whether good or evil. Indeed, Allah knows those who deserve success, and He grants them success and guidance, directing them to perform righteous actions that will earn them His pleasure. He also knows those who deserve failure and expulsion from His great mercy, which amounts to utter failure in this life and the Hereafter for them, we seek refuge in Allah from this evil end