Our Gemara on Amud Beis discusses the obligations of the owner to tend to the firstborn before it is given to the kohen. Additionally, despite the fact that the kohen is entitled to the firstborn, he is forbidden to influence, subtly bribe, or directly pay the owner to choose him specifically as the benefactor of the gift. The decision of which kohen to give the firstborn is at the sole discretion of the owner, with no undue influence.

“Until when must an Israelite tend to and raise a firstborn animal before handing it to the priest? With regard to a small animal, e.g., a sheep or goat, it is thirty days, and with regard to a large animal, e.g., cattle, it is fifty days… If the priest said to the owner within that period: Give it to me, that owner may not give it to him. The Gemara asks: What is the reason? Rav Sheshes says: Because such a priest appears like a priest who assists at the threshing floor so that he can be given terumah. Since this arrangement benefits the owner of the firstborn, as he is spared the effort of taking care of the animal throughout this period, it appears as though this priest has paid for the right to receive the firstborn, which is prohibited.”

There is an interesting halachic inference from the choice of words in this passage. Why is it merely “appearing as though the priest has paid for it”? The owner was obligated to take care of the animal, and instead the kohen is doing it. That is a concrete service and relieves the owner of the obligation. It is not appearing as payment; it IS payment. Therefore, this implies that relief from an obligation is not the same as a financial payment, and this is part of a larger dispute. Consider the following scenario: Reuven owes Shimon $200, and Levi, unsolicited by Reuven, pays Reuven’s debt. Can Levi now ask Reuven to be compensated? Or can Reuven say, “Thank you, but no one asked you to pay on my behalf. I could have found a relative who would have stepped in for me and not charged me, or maybe I would have found a way to convince the lender to forgive the loan. Therefore, why should I have to pay you?” Shulchan Aruch (C.M. 128:1) rules there is no obligation for Reuven to compensate Levi. (This is subject to some debate; see comments of Rama, ibid.)

The Penei Dovid (Devarim 9:27) applies this principle metaphysically. The verse states: God gives bread and sustenance to all flesh (Tehillim 136:25); God obligates Himself to support the poor. Yet the verse also states that if we give charity, Hashem will bless us (Devarim 15:10). But why should God be obligated to reward us? Is this not similar to paying someone else’s debt? However, Penei Dovid says this is why the verse also states (15:11), “…and therefore I command you to open your hand to your brother, the poor and needy.” Meaning to say, this is not coming unsolicited, as God commanded us to support the poor. Even in the case where Levi paid Reuven’s debt, if Reuven requested him to do so, he is absolutely required.

All this is fine and well. I still wonder why the Penei Dovid considered it a question. There is a simpler answer: that perhaps it is so, and God does not owe us for anything. Nevertheless, because He is gracious, He chooses to reward us anyhow, as really with all mitzvos. One answer is that the Penei Dovid might have reasoned that, at the very least, this should refute the halacha and show that indeed there is an obligation if somebody else pays back the loan. However, I think this is weak, because there is a general principle that we do not learn halacha from aggadah. Another answer that occurred to me is that he feels the language of the verse, “therefore I command you…,” explains the reason behind the “therefore”: I commanded you in order that I have a stronger obligation to give reward. That is a little better, but it still does not fit the simple reading of the verse, which reads as follows (15:11): “There will always be poor people in the land; therefore I command you to give charity.” As if to say, poverty is endemic to the human condition and there always will be poor people, and therefore I command you to give charity. The final possibility, and the best answer of the three in my opinion, is as follows. Penei Dovid was aware that all rewards for commandments are not necessarily required, because after all God does not owe us. Yet this is one of the few commandments where a reward (or at least benefit) is stated directly. If so, the point is that God does “owe” us. The question is why. Even though the answer is circular, it does now explain that the verse explicitly had God command it in order to signal that for this mitzvah in particular there is a stronger obligation or commitment by God to give reward. What that actually means is unclear, because God has to keep His word anyway, but somehow or another, by doing this, it is not just a typical reward, but it creates a stronger relationship to the reward. Meaning to say, we know that reward for mitzvos does not always happen directly, promptly, or even in this world. By the fact that there is an “obligation,” it means in some sense it will be more likely to be experienced promptly and/or in this world.