Paul uses this question to emphasize that they are not bragging about themselves. AT: "We are not beginning to praise ourselves again" (See: [[rc://en/ta/man/translate/figs-rquestion]])
Paul says this to express that the Corinthians already know about Paul and Timothy's good reputation. The question prompts a negative answer. AT: "We certainly do not need letters of recommendation to you or from you, like some people do" (See: [[rc://en/ta/man/translate/figs-rquestion]])