What is the ruling when one person affirms drinking from a vessel and another denies drinking from it?

Primary text

If one person states that a dog drank from a vessel, and the other states it dipped its mouth but did not drink, the statement affirming the drinking takes precedence. However, if the affirmation of drinking is not based on certain knowledge, such as the report of a blind person based only on his sensory perception, the statement of the sighted person is preferred because he possesses greater knowledge.