In The Name of Allaah, The Most Merciful, The Bestower of Mercy
Allaah [The Most High] said:
هُوَ أَعْلَمُ بِكُمْ إِذْ أَنشَأَكُم مِّنَ الْأَرْضِ وَإِذْ أَنتُمْ أَجِنَّةٌ فِي بُطُونِ أُمَّهَاتِكُمْ ۖ فَلَا تُزَكُّوا أَنفُسَكُمْ ۖ هُوَ أَعْلَمُ بِمَنِ اتَّقَىٰ
He knows you well when He created you from the earth [Adam], and when you were fetuses in your mothers’ wombs. So ascribe not purity to yourselves. He knows best him who fears Allah and keep his duty to Him.
Few Reminders from the Above Ayah:
Weakness is present and witnessed from you since the time Allaah created you from the earth [i.e. Aadam (alayhis salaam)] and whilst you were in the wombs of your mothers. And even though Allaah [The Most High] place strength in you to perform what you have been commanded, however you have not ceased being weak [i.e. we can never be perfect]. [فَلَا تُزَكُّوا أَنفُسَكُمْ – So ascribe not purity to yourselves]- Meaning: Do not address the people about [yourself] by way of praise. [هُوَ أَعْلَمُ بِمَنِ اتَّقَىٰ- He (Allaah) knows best him who fears Allah and keep his duty to Him]- Meaning: Because indeed Taqwaa is situated in the heart and Allaah [alone] is the One acquainted with its [true reality].
[Ref 1: Source: An Excerpt from ‘Tayseer Al-Kareem Ar-Rahmaan Fee Tafseer Kalaam al-Mannaan’ by Imaam Sadi (rahimahullaah). Publisher: Daar Ibn Hazm. 1st Ed. 1424AH (Year 2003). Slightly paraphrased]