Nahj al-Balagha Hadith n. 360

Selections from The Sayings and Preaching of Amir al-Muminin Ali ibn Abi Talib (Peace Be Upon Him) Including His Replies to Questions and Maxims Expressed for Various Purposes.
Translated by Sayyid Ali Reza

وَقَالَ (عليه ‏السلام):

Amir al-mu'minin, peace be upon him, said:

لاَ تَظُنَّنَّ بِكَلِمَةٍ خَرَجَتْ مِنْ أَحَدٍ سَوءاً،

Do not regard an expression uttered by any person as evil

وَأَنْتَ تَجِدُ لَهَا فِي الْخَيْرِ مُحْتَمَلاً.

if you can find it capable of bearing some good.