The Zohar, chapter “Shmini (On the Eighth Day),” Item 8: All those who engage in Torah cling to the Creator and are crowned in the decorations of Torah. They are loved above and below, and the Creator offers them His right hand, mercy. It is even more so with those who engage in Torah at night, for they have established that they partake in Divinity and join together. And when the morning comes, the Creator decorates them with a single string of grace, so they will be among the higher and among the lower.
There is no time in spirituality. Therefore, “day and night” refer to a person’s inner attitude to his state.
If one’s desires are still uncorrected and egoistic, with the intention “for the sake of oneself,” then he feels that he is in darkness, in the state of night. He cannot bestow and interprets this as the darkness of the night. However, if he can bestow, he immediately considers it day because this state illuminates him.
These states do not depend on how well or poorly one feels, the way we are egoistically accustomed to saying that the whole world is “dark” for us when we feel bad. In the spiritual world, the ability to bestow is called day or Light, and the inability to bestow is called night.
Some people strive to read the Torah particularly during the night, in states of darkness. In other words, they want to correct themselves while in the dark, since there is no correction during the day. During the day, one only performs an action within a desire that was corrected at night.
It is written that the Torah consists of 613 “do’s” (corrections) and 613 “don’t dos” (states of being filled by the Light for the sake of bestowal). Correction occurs particularly at night, during concealment. Meanwhile, reception of Light for the sake of bestowal occurs during the day, because that is when one gains this ability.
The Creator helps the souls that try to perform all of this work to unite by tying them all together with one common thread. When each soul unites with the other souls, it acquires this common big Kli and is therefore able to ascend.
The ascent from one degree to another depends only on the extent of the connection between the souls, which is increased by continually connecting inside a greater and greater desire or Kli. The Creator unites those who perform such corrections at night and continue these spiritual actions during the day. Then, due to their unification, He allows them to rise.