The article examines the rhetorical and linguocultural foundations of teaching rhetorical argumentation in university courses of Russian. The aim of the study is to provide a theoretical grounding for these foundations through the categories of the rhetorical ideal and the ethnic roots of the Russian and Kazakh rhetorical traditions, so as to raise students' motivation and increase the effectiveness of teaching this discipline. The rhetorical ideal is treated as the basis of effective communication that reflects a national picture of the world, while the ethnic foundations of rhetoric are shown to sustain a coherent, value-oriented approach and the constructive character of speech. Taught without moral reference points, rhetoric is easily reduced to a technique of persuasion that slides into manipulation. The methodological basis of the study combines a theoretical review of scholarship on rhetoric, argumentation, pedagogy and speech culture with a historical-cultural analysis of the origins of the two traditions, in particular the rhetorical ideal of Ancient Rus' and the ideal of Kazakh oratory. A comparative method is used to set the two traditions side by side and identify their shared linguistic principles and moral values, and a descriptive-analytical method to systematise the rhetorical postulates, the categories of ethos, logos and pathos, and the features of the rhetorical ideal. The authors argue that introducing these elements into the classroom gives argumentation a constructive footing, while the comparative angle helps students grasp rhetorical principles more fully. The scholarly value of the work lies in demonstrating that the ethnocultural foundations of argumentative discourse can serve as an effective tool for teaching Russian in a multicultural setting; its practical value lies in the use of these conclusions when developing teaching materials and methods that take culturally specific features into account.