The Avnei Nezer (Yoreh Deah 454) asks: when and where did the Jewish people accept the Oaths that prohibit them from leaving exile and taking over Eretz Yisroel? He answers that the Jewish Oaths were imposed on the roots of the Jewish souls in Heaven, and the gentiles' oath was imposed on the angels of each nation.
This fits well with the Zohar (Bereishis 242a), which says in reference to Shir Hashirim 5:8 that the words “daughters of Jerusalem” refer to the souls of the righteous. Here too, Hashem made the souls of the Jewish people swear to keep to the terms of exile. This is similar to the oath administered to the soul before it comes into the world, “Be righteous and do not be wicked” (Niddah 30b).
If every person’s soul swears to be righteous before it is born, what was the purpose of the oath the Jews took when they accepted the Torah? The Avnei Nezer answers that an oath accepted by the soul is not legally binding. It merely means that the soul is infused with a desire to be good. But a person can ignore his soul and follow the evil inclination. The Jews had to take an oath in this world; otherwise they would not have been punished for not listening to the soul.
At this point, the Avnei Nezer is bothered: if the oaths are not legally binding, how could there be a punishment for violating them? He answers that “I will permit your flesh as the gazelles and deer of the field” is not to be understood as a direct punishment, but as a cutting off of Hashem’s protection that comes as a result of the sin. Sometimes even when a person cannot be culpable for what he did, the sin itself distances him from Hashem. We find this in Tikunei Zohar regarding the concept that the Heavenly Court does not judge a person under twenty years of age (Shabbos 89b). Why, then, do people sometimes die under the age of twenty? Because, says the Zohar, “a wicked person’s own sins entrap him” (Mishlei 5:22).
Here too, if the Jews violate the terms of exile and conquer Eretz Yisroel or fight against the nations, Hashem will ask their souls why they did it, and the souls will answer, “We tried our best to push the bodies in the right direction, but they did not listen to us.” Then He will call their bodies in for judgement, but the bodies will reply that they never took any oath; only the souls did. Each has a good excuse, but the connection between body and soul has been ruptured. Hashem’s providence and supervision is removed from the body, and the body is left as ownerless as the wild animals, which have no soul. The Rambam in Moreh Nevuchim (3:17) and the Chinuch in Mitzvah 169 write that Hashem's supervision does not apply to the particulars of each animal but only to the preservation of the species. The same will be the case for a human being who distances himself from his soul.
Of all wild animals, the gazelle and the deer are singled out because they are used elsewhere as the symbols of detachment from holiness. In three places, when the Torah wants to teach us that meat is not holy, it says “like the gazelle and the deer.” Devarim 12:15, says Rashi, is talking about sacrificial animals that became blemished and were redeemed with a replacement animal. The new animal is brought as a sacrifice instead, and the blemished one may be eaten as plain meat without any special restrictions. The Torah uses the same comparison in 12:22 when referring to plain meat that was never designated as a sacrifice, and in 15:22 when referring to a firstborn animal that became blemished and is permitted to eat as plain meat.
In two out of those three places, the Torah is discussing meat that was once holy but now its holiness has been removed. Here also, the result of violating the oaths of exile is that one is cut off from his source of holiness and removed from Hashem’s supervision, may Hashem spare us.