Hazrat Sa’d (radhiyallahu ‘anhu) was a person of Allah Ta‘ala and a man of justice. If he saw anything wrong then he would correct the situation for the sake of Allah Ta‘ala. He could not bear to witness oppression and tyranny take place. Hence, after stopping a person from wrong, if the person persisted, then he would turn to Allah Ta‘ala and make du‘aa against the person.

Qais bin Abi Haazim (rahimahullah) mentions, “On account of the du‘aa of Rasulullah (sallallahu ‘alaihi wasallam), whenever Hazrat Sa’d (radhiyallahu ‘anhu) would make du‘aa, it would be accepted. The people were well aware of this and thus feared earning the curse of Hazrat Sa’d (radhiyallahu ‘anhu).”(Usdul Ghaabah 2/308)