وَلِيُمَحِّصَ اللَّهُ الَّذِينَ آمَنُوا وَيَمْحَقَ الْكَافِرِينَ ١٤١

And this is (also) with the intention that Allah may bring (more) refinement to the believers (i.e., cleanse and purify them) and annihilate the disbelievers. (3:141)