John Gill Bible Commentary

And your tires shall be upon your heads, and your shoes upon your feet..... As will be necessary while travelling, and when carrying captive to a foreign country, as now will be their case: ye shall not mourn nor weep; shall not dare to do it, because of their enemies; and, moreover, so great should be their miseries and calamities, that they should be struck dumb, and quite astonished and stupefied with them; that they should not be able to vent their sorrow by an outward act of mourning: but ye shall pine away for your iniquities; without any true sense of them, or godly sorrow for them, but in wretched hardness of heart, and black despair: and mourn one towards another; not to God, confessing their sins, being contrite and penitent; but to one another, fretting, murmuring, and complaining at the hand of God upon them: this seems to denote the private way of mourning they should use for fear of the enemy, when they could get together by themselves, as well as their disregard to God, against whom they had sinned.