Ali: Who has time to dwell on others’ faults?

How do people find the time to criticize others over every small mistake?
‘Ali ibn Abi Talib seems to have a theory:
The person who sees their own shortcomings has no time to dwell on other people’s faults.
In Arabic:
من أبصر عيب نفسه شغل عن عيب غيره
Arabic vocabulary
- man (من) – whoever, anyone
- absara (أبصر) – notices
- ‘ayb (عيب) – defect
- nafs (نفس) – self
- shaghala (شغل) – be busy, stay occupied
- ‘an (عن) – from (as in "kept away from something")
- ghayr (غير) – other, someone else
Notes
- This quote is from a famous collection of material attributed to ‘Ali: Dustur ma‘alim al-hikam by al-Qadi al-Quda’i (d. 1062).