In the art of rhetoric, the principle of the speaker's authority (ethos) is one of the three principles of speech, which, along with the other three principles, namely pathos (arousal in the audience) and logos (logical reasoning), form the sides of the "triangle of persuasion", which has a great importance and impact on the audience. The examination and careful consideration of the content of the words of Amir al-Muminin indicates that he has used this rhetorical device in many positions and according to the time and place, and it is one of the most important reasons for the inclusion of the Nahj al-Balagha in the list of primary rhetorical works in history concerns considering such subtleties in rhetoric. The point that is raised in the meantime is that observing the principle of the speaker's authority, which in itself implies the speaker's definition and praise of his virtues, can be combined with the virtue of humility and modesty, which is the virtue of all ethical people, especially Amir al-Muminin (AS). As we will see in the examples, throughout Nahj al-Balagha, wherever the Imam had to comply with the principle of eloquence, there was an expedient that he mentioned to justify his virtues. In other words, the words of Amir al-Muminin in expressing his unique qualities are only to prove his truthfulness in his words, actions, character and way of life, which of course is in complete contrast with self-praise, arrogance and pride.