An-Nisaa • BN-TAFSEER-IBN-E-KASEER
﴿ أَلَمْ تَرَ إِلَى ٱلَّذِينَ يُزَكُّونَ أَنفُسَهُم ۚ بَلِ ٱللَّهُ يُزَكِّى مَن يَشَآءُ وَلَا يُظْلَمُونَ فَتِيلًا ﴾
“Art thou not aware of those who consider themselves pure? Nay, but it is God who causes whomever He wills to grow in purity; and none shall be wronged by as much as a hair's breadth.”
Please check ayah 4:52 for complete tafsir.