אמור אל אהרן קח מטך…ויהיו דם (וארא ז:יט)

Rashi explains why Ahron had to hit the water and not Moshe, for the waters carried him when he was thrust into the River Nile in a basket, and therefore, it would be ungrateful for him to hit the water.  This is how gratefulness should be viewed: The story with Moshe in the basket happened 80(!) years before he was told to bring the ten plagues upon the Egyptians – still, he was not allowed to hit the water!

Here is a story that teaches us how to be grateful – even after many years have passed:

During the first years that Maran Reb Aharon of Belz zt”l lived in Tel Aviv, there was a bochur who used to learn in his Beis Medrash every Friday night while Maran led the Shabbos Tish on the other side of the Beis Medrash. In those times, there were many Shabbosim where there was not a minyan for bentching at the tisch, and the bochur was asked to join as a tenth to be able to bench with “נברך לאלוה-נו.”

The bochur became engaged and traveled to America.  Since he did not hail from a Chassidishe family, it did not occur to him to take leave from Maran Reb Aharon of Belz.

Years later, this bochur – now a married man with a wife and kids – traveled for Shavuos to his parents living in Eretz Yisroel.  On the first night of Shavuos, after davening and eating the seudah, he wondered to himself where he would find a minyan to daven “יום טוב שני” the second day of Yom Tov (as in Eretz Yisroel, they only keep one day Yom Tov). He went to inquire in the Belz Beis Medrash if there would be a minyan on the second day for people who arrived from חוץ לארץ – outside Eretz Yisroel. 

As soon as he posed his question, the door suddenly opened, and Maran Reb Aharon entered the Beis Medrash to daven.  Maran approached the guest and asked: “Where were you all this time? I still owe you a thank you for joining our minyan for Birkas Hamazon!”.  Maran thanked him and blessed him.