Adam Clarke on Matthew 8:31

Suffer us to go away - Επιτρεψον ημιν απελθειν: this is the common reading; but αποστειλον ημας, send us away, appears more likely to be genuine. This latter reading Griesbach has adopted, on the authority of three ancient MSS., the Coptic, Sahidic, Ethiopic, Syriac, all the Arabic, Saxon, most of the Itala, and the Vulgate. Send us away seems to express more fully the absolute power Jesus Christ had over them - permission alone was not sufficient; the very power by which they were to go away, must come from Christ himself! How vain was the boast of Satan, Mat 4:9, when we find he could not possess the body of one of the vilest animals that God has made, without immediate authority from the Most High! Since a demon cannot enter even into a swine without being sent by God himself, how little is the power or malice of any of them to be dreaded by those who have God for their portion and protector!