One of the sections of Moshe’s farewell speech opens with a reiteration on how important it is that people put in real effort:

וְהָיָה עֵקֶב תִּשְׁמְעוּן, אֵת הַמִּשְׁפָּטִים הָאֵלֶּה, וּשְׁמַרְתֶּם וַעֲשִׂיתֶם, אֹתָם-וְשָׁמַר ה אֱלֹהֶיךָ לְךָ, אֶת-הַבְּרִית וְאֶת-הַחֶסֶד, אֲשֶׁר נִשְׁבַּע, לַאֲבֹתֶיךָ – When you will listen to the laws, observe and perform them; Hashem will safeguard you, and uphold the covenant sworn to your fathers. (7:12)

The Alshich points out the peculiarity of the word עֵקֶב – it is very infrequently found. In addition to which, it doesn’t even seem to change the basic message in the context – were it not to say עֵקֶב, the meaning would remain the same – it hasn’t even been translated above, for this reason.

It seems to be a conditional term, but this raises an issue – in Judaism, we do not perform our duties like workers with the expectation of reward at the end. We are meant to dedicate ourselves regardless. So what is the implication of the conditional incentive clearly stated?

R’ Shlomo Ganzfried explains that the reward is not actually for the net result of the action performed.

The Gemara in Berachos tells how R’ Zeira took a short break from his learning, left the study hall, and decided to sit on the steps outside; so that if a rabbi walked by, he could stand up out of respect and deference, gaining merit while nonetheless being idle from learning.

This evidently indicates that positive attitude and care are independently valuable characteristics to display and exercise, outside of the set mitzvos and laws.

Similarly, the Torah requires anyone who witnesses an event to not withhold testimony. This also means that a witness can not be paid to testify – they are already obligated. However, if someone is hired to investigate something, and they find evidence or the like, they can be still be paid, not violating the above requirement.

This is because they are not being paid for the testimony or presentation of evidence. The payment is for the work and effort put in.

The same is true of the Torah’s affirmation of the reward, exemplified by the story of R Zeira. There may be no reward for the actual mitzva in this world – but showing respect for the accoutrements of Torah is very different.

This is why it is specifically here that the word עֵקֶב – literally “heel” – appears here. It is not conditional on performance at all; indeed, the Torah must be observed under any and all circumstances.

But the legwork, the walking, the effort, are what matters. That makes all the difference. This is the imagery of עֵקֶב.