The First Blood Shed for the Cause of Islam

Muhammed bin Ishaaq (rahimahullah) narrates:

The Sahaabah (radhiyallahu ‘anhum) of Rasulullah (sallallahu ‘alaihi wasallam) would (in the early days of Islam) go into the valleys when performing Salaah so that they would be able to keep their Salaah hidden from the disbelievers (and thus avoid persecution). Once, while Hazrat Sa’d (radhiyallahu ‘anhu) was with a group of Sahaabah (radhiyallahu ‘anhum) in one of the valleys of Makkah Mukarramah, a group of disbelievers discovered them and began to condemn the Sahaabah (radhiyallahu ‘anhum) and criticize their Deen. This led to a fight breaking out between these Sahaabah (radhiyallahu ‘anhum) and the disbelievers, during which Hazrat Sa’d (radhiyallahu ‘anhu) inflicted a head wound to one of the disbelievers by striking his skull with the jaw bone of a camel. This was the first fight (from the beginning of Islam wherein the Sahaabah (radhiyallahu ‘anhum) wounded the kuffaar and) in which blood was shed for the cause of Islam. (Usdul Ghaabah 2/308)