The error here is that Rabbi Chaim Vital was not referring to the Jewish people's oath not to end the exile with their own actions. He was referring to Hashem's oath and Hashem's decree of exile itself. Rabbi Chaim Vital was not the first to speak of this thousand-year limit to exile; it was written hundreds of years earlier in the Zohar Bereishis 117a that the decree of exile was “one day and no more”, as Scripture states, “All the day lonely” (Eichah 1:13). As we know, G-d’s one day is a thousand years (Tehillim 90:4). Rabbi Chaim Vital mentions this Zohar.

The Zohar Shemos 17a repeats this same prediction of 1000 years, and then adds, “And if it will be more [than 1000 years] that will not be due to a decree of the King, but because they do not want to repent to Him.” So we see that within 1000 years of the destruction of the Temple, even repentance would not have brought the redemption.

We see a similar concept expressed in the Talmud Avodah Zarah 9a and 9b, only the number is not 1000; it is 400 (according to Rabbi Chanina) or 172 (according to the Baraisa that holds the Days of Moshiach begin at the year 4000, and the destruction of the Temple was in 3828).

The inflexable part of the decree of exile – during which repentance does not work – is enforced by G-d’s oath. The Talmud mentions this oath in Bava Basra 74a, where G-d says, “Woe is Me that I have sworn, and now that I have sworn who can annul My oath?”

This is not to be confused with the oath in Kesubos, which G-d placed upon the Jewish people not to force the end of exile or go up as a wall. That oath is incumbent upon us, whereas the oath in Bava Basra is incumbent upon G-d, so to speak.

Rabbi Chaim Vital aggadically explains one of the oaths in Shir Hashirim to be referring to G-d’s own oath. Thus he explains the oath: “I swear to make the exile last ad shetechpatz – until the Jewish people repents completely and serves Me purely out of love.” Rabbi Chaim Vital then adds that this is only for 1000 years; after that the exile is no longer enforced by G-d’s oath, but can end anytime the Jews repent, even if they repent out of fear of punishment and desire for reward. After all, one who does mitzvos only to get the reward is also a good Jew, and that is considered repentance. But the extra-high level of serving Hashem out of love is so great that it could bring the redemption even before the 1000-year time frame.

In any case, Rabbi Chaim Vital is not touching at all upon OUR oaths, which are a Torah law like any other law and are not subject to any time limits.