Moses received Torah from Sinai and passed it on to Joshua. Pirkei Avot 1:1
Moses was able to receive Torah because of his great humility, as it is written, “The man Moses was very humble” (2), and this is one of the forty-eight attributes through which Torah is acquired (3). Humility is the foundation of divine service, Torah, and prayer, for according to the extent of your humility can you receive the holiness of the Creator. This is according to the principal of “measure for measure”: if you humble yourself, G!d does the same, so to speak, limiting the divine power so that you, a mere mortal, can receive it. But if you take pride in your divine service and believe you are serving G!d to your fullest, then G!d does likewise and refuses to limit His glory, so no mortal can receive it.
Do not be like servants who serve their master expecting to receive a reward; rather be like servants who serve their master unconditionally, with no thought of reward. And the awe of Heaven shall be upon you. 1:3
The word for reward, pras, also means “separation.” This is fitting, because when you expect to be paid for your work, that payment is separate from the work. But in divine service there should be no separation; rather, through the service you should cleave to G!d. This is the meaning of “The reward of a mitzvah is mitzvah” (4), that is, cleaving to G!d, for mitzvah can also mean “attachment.” This in itself is the greatest reward of a mitzvah: that you, a mere mortal, can attach yourself to the infinite G!d. The conclusion of the teaching, then, is the result: when you serve G!d and cleave to Him, then the great awe of Heaven will be upon you, as it is upon the angels, who comprehend much more fully than we the transcendent infinity of G!d. (5)
1) It’s tradition to study one chapter of Pirkei Avot each Shabbat, starting after Pesach 2) Number 12:3 3) see Pirkei Avot 6:6 4) Pirkei Avot 4:2 5) The conclusion is usually translated as a remonstration: “Let the awe (of fear) of Heaven be upon you,” but the Hebrew allows for the Kozhinitzer’s reading just as easily.