"Ben Azai said: The reward of a Mitzvah is a Mitzvah."
The performance of a Mitzvah awakens joy in the soul of man. What’s more, the delight and joy that we experience through performing the Mitzvah is a separate Mitzvah, in and of itself. That is, HaShem counts the pleasure and happiness that we feel when we do a Mitzvah as an independent Mitzvah.
Therefore, whenever we perform one Mitzvah, we are actually performing two Mitzvoth. Accordingly, for each Mitzvah that we perform HaShem grants us a double reward. Specifically, HaShem rewards us both for the Mitzvah, itself, as well as, for the Mitzvah of experiencing the joy of the Mitzvah.
In this light, King David said (Tehillim 68:4), "The righteous will be glad, they will delight before HaShem; they will rejoice with happiness." Meaning, the righteous will "be glad and delight" in the Mitzvah that they perform; additionally they will "rejoice with the happiness" of the reward of the Mitzvah that HaShem grants them.
The Talmud tells us (Pesachim 68b) that when Rabbi Sheshes would complete the review of his studies, he would sing, "Rejoice, O my soul, Rejoice O my soul." What is the significance of twice repeating the phrase? Rabbis Sheshes’ intention was first to ask rhetorically: "In what shall my soul rejoice?" Then he responded, "My soul should rejoice in the very joy of the soul that delights in the study of Torah!"
[Based on the commentary of the Chidah to Pirkei Avot]
TODAY: When you perform a Mitzvah, discover the joy that awakens in your soul - and rejoice!
Reprinted from: The Salant Center eMussar - The Wisdom of Personal Growth