Shake off the dust of your feet.
-The sin of the Sodomites was single, but that of those rejecting the apostles would be manifold, including
(1) infidelity;
(2) disobedience;
(3) ingratitude;
(4) inhospitality;
(5) rebellion and contumacy against God, contrary to the law of nature, and in defiance of the grace of God. (Lapide.)
The danger of defilement
The danger of course was not from dust on the feet, but from defilement on the life and in the heart. Every apostle was to let his impenitent countrymen know that they were “as heathen men in the sight of the Messiah,” impure in the estimation of the infinitely Holy One. The spirit of the injunction runs through all the ages, and has come down to our day. Its spirit, but its spirit only. And hence a very heavy responsibility rests on that minister of the gospel who gives no intimation of any kind to the impenitent with whom he associates, that they are impure in the sight of God, and in danger of eternal separation from the good. (James Morison, D. D.)