Kabbalah Maleakhi 3:16: Pri Etz Chaim

However the last kaddish is not included in these, since all of the worlds already ascended. Indeed, this kaddish is called the orphan's kaddish. The explanation is that the secret of this kaddish is that it is in order to raise up all the dead souls, with the secret of the revival of the dead. And that is why orphans, whose fathers and mothers have died, say it. And the idea is that it has [God's] name of 42 [letters] in a different way, and it is hinted at in the washing of the hands. And you should know that through the name, bet, mem, vav, kaf, samech, zayin [letters spelling out, our God, in a letter substitution scheme], there is revival, through the secret of: I kill and I bring to life (Deuteronomy 32:39). As this name is in Gevurah [Might]; and with that which the Holy One, blessed be He, kills, with that same thing He brings to life. That is why before this name, there is the name, kaf, vav, zayin, vav [letters spelling the tetragrammaton according to the same scheme]. As its numerical count is tal [dew], with which the dead will be revived. But you should know that the addition of Shabbat extends throughout the Shabbat day. However on mundane days, the additional holiness is only at the time of prayer. That is why there is only an addition to the soul exclusively on Shabbat. But nevertheless, for those that fear the Lord and for those who esteem His name (alluding to Malachi 3:16), there is a little enlightenment during the time of prayer even on mundane days. And understand this. There is another distinction, that the addition of holiness on Shabbat comes by itself from all of that which we do on mundane days through our prayers. There is yet another distinction, that on Shabbat all of the worlds ascend; whereas during mundane days, it is only the existence of the souls that ascend together with the divine presence through the secret of the feminine waters.