The Torah is very explicit when it comes to revealing the punishment for a crime, not so when it comes to rewarding for a Mitzvah. There are many reasons for this both revealed and concealed. Rabbenu Bachya will explain to us a few of these reasons: We can not understand what the soul will feel and in what form in the World to Come, and so trying to explain the experience is futile.
Pg 435/ 437
Nefesh Hachayim
At first glance, the teaching of the Avos seems simple and concise. At a closer look, the immense depth and teachings they hold are revealed.
Gate three, Chapter 1 pg 107