A certain person was once speaking ill of Hazrat ‘Ali (radhiyallahu ‘anhu), Hazrat Talhah (radhiyallahu ‘anhu) and Hazrat Zubair (radhiyallahu ‘anhu). Seeing that this person was speaking ill of the Sahaabah (radhiyallahu ‘anhum), Hazrat Sa’d (radhiyallahu ‘anhu) immediately tried to stop him saying, “Do not speak ill of my brothers!” However, the person refused to desist.
Hazrat Sa’d (radhiyallahu ‘anhu) thus stood, performed two rakaats of salaah, and made du‘aa against this person who was speaking ill of the Sahaabah (radhiyallahu ‘anhum). Shortly thereafter, a camel arrived, pushing its way through the people. The camel seized this person and trapped him between its chest and the ground, crushing him to death.
Hazrat Sa‘eed (rahimahullah) concludes saying, “I then saw the people walking behind Hazrat Sa’d (radhiyallahu ‘anhu) saying, ‘Congratulations, O Abu Ishaaq! Your du‘aa was accepted (in defense of the Sahaabah)!’”
(Siyar min A’laam min Nubalaa 3/73)