Chapter 8 Verse 1
The verse states that All the commandment that I command you today you shall observe to perform, so that you may live and increase, and come and take possession of the land that Hashem swore to your forefathers.
Rashi brings the Midrashic idea that if you begin something you should complete it. Because the person who completes it that whose name it is that the Mitzvah is attributed to.
Rabbi Dubin’s thoughts
The commentators wonder why the word Hamitzvah is used, in singular, it should have been written Mitzvos, in plural?
Using the idea of Gur Aryeh that Mitzvah is written to mean the entire Torah and Rashi’s understanding, that each Mitzvah is called by the person who performs it, we understand that every Torah precept can be acquired by each individual.
Hashem wants to bestow merit on each and everyone of us. As individuals each individual may not be able to complete every Mitzvah but as a whole each one of us has unique characteristics that as a community we can complete it all. Kol Yisrael Arevim Zeh Lazeh, each Jew is reponsible for each other and it is a responsibility of the Jew to find his/her Mitzvah.
This Drash was with the help of Saperstein Edition of Artscroll Chumash