je toon akal lateef,
kaale likh na lekh
aapne girevaan mein,
sir neevan karke vekh
Reference: Kalam Baba Farid, Dr Nazir Ahmad; Packages Limited; Page 20 ( view source )
English Translation
Fareed, if you have a keen understanding, then do not write black marks against anyone else. Look underneath your own collar instead.
Translation: S. S. Khalsa