Caution: Translations of Quran and Ḥadīth may lead to possible misapplications and misinterpretations. This site is intended for students of sacred knowledge that are proficient in comprehending classical Arabic and have a strong foundation in Islamic sciences. Also note that religious injunctions rely on several aspects beyond what one may glean through reading individual aḥādīth.
quran:4:49

Have you not seen those who claim themselves to be pure? Rather, Allah purifies whom He wills, and injustice is not done to them, ˹even˺ as much as a thread ˹inside a date seed˺.  

Have you not seen those who praise themselves for purity? namely, the Jews, when they say, ‘We are God’s children and His beloved’, in other words, it is not a matter of their purifying themselves. Nay, God purifies whom He will, through faith, and they shall not be wronged, they shall not be diminished of their deeds, a single date-thread, as much as the peel on a date-stone.
القرآن:٤:٤٩

أَلَمْ تَرَ إِلَى الَّذِينَ يُزَكُّونَ أَنْفُسَهُمْ ۚ بَلِ اللَّهُ يُزَكِّي مَنْ يَشَاءُ وَلَا يُظْلَمُونَ فَتِيلًا  

{ألم تر إلى الذين يزكُون أنفسهم} وهم اليهود حيث قالوا نحن أبناء الله وأحباؤه أي ليس الأمر بتزكيتهم أنفسهم {بل الله يزكّي} يطهر {من يشاء} بالإيمان {ولا يُظلمون} ينقصون من أعمالهم {فتيلا} قدر قشرة النواة.