All the devils - Παντες, all, is omitted by many MSS. and versions; Griesbach leaves it out of the text. Οἱ δαιμονες is omitted also by several: Griesbach leaves it doubtful. Probably it should be read thus, And they besought him, saying.

And all the devils besought him,.... The whole legion of them, not only their chief, in the name of the rest, but all of them earnestly entreated him; they were all humble supplicants, not from love, but fear, and with a view to do mischief: though the word "all" is omitted in some copies, as it is in the Vulgate Latin, Syriac, and Persic versions; neither has the Ethiopic the word devils, but both are retained in the Arabic version:
saying, send us into the swine, that we may enter into them. The Persic version renders it, "seeing thou drivest us from the man, give leave that we may enter into the swine": which is rather a paraphrase than a version, and expresses the sense very well. They chose to be any where, rather than depart the country; and especially than to be sent into the deep, the abyss, or bottomless pit; and they chose to be sent into the swine, as being impure creatures like themselves; and no doubt with a view to destroy them, that they might satisfy themselves as much as they could with doing mischief; though not to that degree they would, nor to those persons they were desirous of; and so bring as much odium and reproach upon Christ as they could, who gave them leave. The devils are unwearied in doing mischief, they cannot rest unless they are about it; and they choose to be concerned in doing it in a lesser way, if they are not allowed to do it as largely as they would; if they are not suffered to touch the lives of men, or ruin their souls, it, is some satisfaction to them to be suffered to hurt their bodies; and if that is no longer permitted, rather than be doing nothing, they are desirous of doing injury to irrational creatures, the property of men; all which shows the malice and wickedness of these evil spirits: See Gill on Matthew 8:31.

And all the devils besought him, saying--"if thou cast us out" (Matthew 8:31).
Send us into the swine, that we may enter into them--Had they spoken out all their mind, perhaps this would have been it: "If we must quit our hold of this man, suffer us to continue our work of mischief in another form, that by entering these swine, and thus destroying the people's property, we may steel their hearts against Thee!"