Dai- Dai- Einu…
Chassidim have a tendency of finding lessons in Jewish practices on the basis that “if they are not prophets, they are the ‘children of prophets'”. (“Children of prophets” is an idiom in Tanakh for those studying for prophecy.) Along those lines…
I don’t know about the rest of you, but I lack the patience to sing the entire Dayeinu, all 15 stanzas, to that “Dai, dai-, -einu, dai-, dai-, einu…” tune. So, we tend to only bother every fifth stanza or so.
However, even something as late and as trivial as this may have a deep holy lesson for us!
From the Y-mi Berakhos 67b-68a, in a discussion of things that the sages decreed down below and was ratified in the heavenly court:
R’ Avun in the name of R’ Yehoshua ben Levi: Even maaser [tithes, which is rabbinic when the majority of Jews aren’t living in Israel]. As it says (Malakhi 3:10) “Bring all the maaser[, so that there may be foor in My house… would I not open the windows of heaven and pour for you a blessing ad beli dai]”
What is “ad beli dai” [until there is no enough]?
R’ Yosi bar Shim’on bar Ba in the name of R’ Yochanan: Something that is impossible to say about it “enough” is a berakah.R’ Berachah, R’ Chelbo, and R’ Aba bar Ilai [68a] in the name of Rav: until your lips tire of saying “dai — enough”.
So it would seem there is value to a tune that thanks Hashem for all the berakhos He bestowed on us during the Exodus that tires out our lips saying “dai“!