Moral education plays a significant role in the felicity of individuals and society. That is why it is considered to be one of the most important goals of the resurrection of the Holy Prophet. Educational thinkers have always been concerned with the correct way to educate human beings. In this process, thoughtfulness has received much attention because it is the origin of most human behaviours. Interrogation is a salient method to activate human’s thought. Accordingly, the present research with a descriptive-analytical method, intends to illustrate interrogation and its functions in moral education with examples from Qur'an and Nahj al-Balagha. Motivating thoughtfulness, awakening human nature, encouraging people to ethical action, changing perspectives, and creating the correct insight, enriching knowledge with reasoning, controlling ‘self’ and its unbridled tendencies, and giving correction time to the learner were found to be the most important functions of the interrogation in moral education. The adoption of interrogation for moral education leads to the awareness of individuals and the clarification of the dark sides of ethical characteristics and actions, as well as making education a dynamic and critical process.