According to Catholicism how does a person discriminate between hearing the true word of God versus a hallucination or a demon?

How does the Catholic Church answer this question: Suppose you hear God make you a commandment, how do you differentiate that from either your own internal monologue or from an imposter angel or demon, a hallucination or of the word of God himself? I don’t mean to ask advice for myself, but in a general sense, how does a person differentiate between the word of God as many describe hearing in the bible from an illusion or an imposter.