Zohar I 186b
All souls are subject to reincarnation;
and people do not know the ways of the Holy One, blessed be He! They do not know that they are brought before the tribunal
both before they enter into this world and after they leave it; they are ignorant of the many reincarnations and secret works
which they have to undergo, and of the number of naked souls, and how many naked spirits roam about in the other world without
being able to enter within the veil of the King's Palace. Men do not know how the souls revolve like a stone that is thrown
from a sling. But the time is at hand when these mysteries will be disclosed.
Zohar II 99b