John Calvin on Matthew 9:30-31

30. And Jesus threatened them Either he wished to have other persons as witnesses of the miracle, or to delay the publication of it till another time. Their conduct in immediately proclaiming it every where is worthy of blame: for the notion entertained by some, that Christ forbade them for the purpose of exciting them the more, has been already refuted. There was, no doubt, some reason for forbidding it, which is unknown to us; and those men, through inconsiderate zeal, spread the rumor before the proper time.