[Avodah] Hakarat Hatov

[Micha Berger via Avodah]

PS: I started with the aggadic story and didn't say why I opened with
a medrash rather than a gemara.

The Nile and the sand wasn't actors. Moshe didn't really owe them
anything. It's like "not embarassing" the challah by covering
it. Apparently the notion of repaying a favor is so important, HQBH
expects us to practice it for a middah exercise even when the other side
isn't a real 2nd party.