Matthew 8:30-32

And there was a good way off from them That is, at a considerable distance, although, it seems, within their view; a herd of many swine Which it was not lawful for the Jews to keeps much less to eat: yet great numbers of them were bred up in that extreme part of the country, out of regard to the gain of such merchandise, for they sold them to the Roman soldiers, and other Gentiles, who were very numerous in these parts. So the devils besought him For they were entirely in his power, and under his control; saying, if thou castest us out Which they suspected he would do; suffer us to go into the herd of swine By making this request the devils acknowledged that it was not in the power even of a legion of them to do any mischief to so contemptible a creature as a swine without Christ's permission, far less could they destroy the man in whom they lodged. Indeed the whole of this history teaches us to rely on the providence of God, and not to live in fear of evil spirits. They are under the strictest restraint, and cannot hurt us without the divine permission. Mark says that they first besought him much, that he would not send them out of the country; and Luke, that he would not command them to go into the deep, εις αβυσσον, into the abyss, meaning, doubtless, the place where wicked spirits are punished. By requesting to be permitted to enter into the swine, “they doubtless proposed to prevent any good effect which the miracle of delivering the men from their power might have had on the Gadarenes, and to render Christ odious to that wicked people.” Their design could not be hid from Jesus, nevertheless he granted their request, “not only because he knew it would render the miracle more public, but because it would prove the reality of the possession, and make men understand both how great the power of evil spirits is, and how terrible the effects of their malice would be, if they were not restrained. For no sooner was the permission granted, than the keepers, who were with the swine, and the disciples, who were at a distance, beheld, to their great astonishment, the whole herd running furiously down the mountains, and leaping from the tops of the rocks into the sea, where they were drowned, to the number of two thousand; while the possessed furious madmen became all of a sudden meek and composed, having recovered the entire use of their reason, the first exercise of which doubtless would lead them to a high admiration of his goodness, who had delivered them from the oppression of the devil. Jesus might permit the devils thus to fall on the herd as a punishment also to the Gadarenes for keeping swine, which were a snare to the Jews, and to make trial of their disposition, whether they would be more affected with the loss of their cattle, than with the recovery of the men, and the doctrine of the kingdom. Whatever were the reasons, it is certain that, though he might rightfully have used all men's properties as he pleased, yet this, and the withering of the barren fig-tree, are the only instances wherein man suffered the least damage by any thing our Lord ever did. However, neither the owners of the herd nor of the fig-tree could justly complain of their loss, since the good of mankind, not in that period and corner only, but in every succeeding age, through all countries, has been so highly promoted at such a trifling expense to them.” “No miracles are more suspicious than pretended dispossessions, as there is so much room for collusion in them; but it was self-evident that a herd of swine could not be confederates in any fraud: their death, therefore, in this instructive and convincing circumstance, was ten thousand times a greater blessing to mankind than if they had been slain for food, as was intended.” See Macknight and Doddridge.