John Calvin on Mark 1:34-37

Mark 1:34. He did not permit the devils to speak. There might be two reasons why he did not permit them: a general reason, because the time of the full revelation was not yet come; and a special reason, which we hinted at a little ago, that he refused to have, as heralds and witnesses of his divinity, those whose praise could have no other effect than to soil and injure his character. This latter reason is undoubtedly true: for he must have known, that the prince of death, and his agents, are in a state of irreconcileable enmity with the Author of eternal salvation and life.