It is reported that Al-Ḥasan Al-Baṣrī said:

Son of Ādam, you will never find the reality of īmān as long as you fault people for doing what you yourself are guilty of, until you clear yourself of that fault and correct it. Then, you will not correct a fault in yourself except that you will notice another, so your occupation will become correcting yourself, and this is the most beloved thing to Allāh, when you are like this.

Al-Khaṭīb Al-Baġdādī, Al-Muntakhab min Al-Zuhd wa Al-Raqāʾiq, article 41.