The article examines the changes caused by historical events in the language of oaths created in the Eastern Slovak city of Levocha for several centuries. These events include the transfer of several neighboring cities as collateral to the Polish Kingdom, the increasing importance of Western Slovakia after the inclusion of most of the Hungarian Kingdom into the Ottoman Empire, the Reformation and recatolization of the population. At the same time, the language of the monument demonstrates that the trends in the development of its language, despite the deviations, generally coincided with the general Slovak ones, which led to the unification of the written language according to the Southwestern Slovak model, although with minor regional differences.