The Battle of Siffin happened in the year 37 AH, in the land of Siffin located in the western part of Iraq between Raqqa and Bals. It was fought between Imam Ali (AS), the head of the Kufa army, and Mu'awiyah ibn Abu Sufyan, accompanied by the people of Sham (i.e. Syria). One of the important points of this battle that has not been studied methodologically so far is the unity and coherence of the Syrian Army. This issue has been mentioned by Imam Ali in Sermon No. 25 in Nahj al-Balaghah when describing the army of Syria. Furthermore, most historical sources acknowledged it. The present study uses the critical discourse analysis method - as an interdisciplinary approach in social sciences that examines the relationship between language, power, ideology and discourse - to understand the impact of Mu'awiyah's speech on this unity and cohesion. Therefore, the effect of Mu'awiyah's speeches on his army will be examined at three levels of description, interpretation and explanation. The results show that Mu'awiyah used both tradition and religion to produce motivating and unifying factors among the people of the Sham.