Tanya Chapter 40 part 4

A tiny being can initiate vast positive change. When a person learns and prays out of love and fear, the letters he utters are “alive” with spiritual infusion and they rise to the ten sefirot. There, their true identity as the completely unbounded light of Hashem is exposed. In this world below, the radiance of Torah and mitzvot cannot shine, but in the coming future when the world rises out of its materiality, all of that will change.

Now, something amazing happens when Torah and mitzvot –– which are the Divine will –– rise to become incorporated within the ten sefirot. The Divine will, which far transcends the sefirot, illuminates them and causes the middot to fuse, “sweetening” the attributes of severity with kindness, thus bringing an increased flow of Divine kindness into our world. And all of this is set into motion by our fulfilling the Torah and mitzvot out of the desire to attach to Hashem in love and out of feelings of awe for Him.