Is there a limit to rewards on single acts?

Question

According to the principle of kam lei b'derabah minei קם ליה בדרבה מיניה a single improper act incurs the strictest penalty even if more than one violation occurs.

Is there a parallel limit to the number of or type of reward (physical/spiritual/this world/the next) one earns if a single act satisfies two separate positive obligations simultaneously? If I perform an act that calls forth, biblically, two separate rewards (say "long life" and "the land yields fruit") do I only get rewarded with the 'stronger' one? Is the merit written in the 'book of remembrance' which is used to judge me on Yom Kippur reflective of more than one simultaneous merit?

Answer 1

It is important to note that קם ליה בדרבה מיניה is a principle governing punishments imposed by a court. That is, a Beit Din cannot impose a monetary penalty where the same act also incurred a more serious punishment.

However, as pointed out by Or Zarua' Bava Kama 303:

כל קם בדרבה מיניה חייב בבא לצאת ידי שמים

In every case of kam lei b'derabbah mineih, one is nonetheless obligated in order to fulfill one's heavenly duty.

As noted by Or Zarua', this is spelled out in more detail by Rashi to Bava Metzi'a 91a:

אפילו במקום מיתה נמי רמו תשלומין עליה אלא שאין כח לענשו בשתים אבל ידי שמים לא יצא עד שישלם

Even where someone incurs the death penalty, the financial obligation is still incumbent upon him. It's just that [the court] does not have the power to punish him twice, but he has not fulfilled his heavenly duty until he pays.

So even where Beit Din won't impose a financial penalty because of kam lei b'derabbah mineih, the guilty individual really ought to pay up anyway.

That being the case, the analogy to rewards for mitzvot falls away. G-d will (presumably) reward someone in full for whatever righteous actions they perform, even if one action is deserving of more than one discrete reward.