Sahih Muslim Book 19, Hadith Number 4371.

Chapter : Justification for killing those guilty of breach of trust and making the people of the fort surrender on the arbitration of a just person.

It has been narrated on the authority of Hisham (who learnt it from his father) that the Messenger of Allah (may peace be upon him) said (to Sa’d): You have adjudged their case with the judgment of God, the Exalted and Glorified.