Parshat Vaetchanan, chazal tell us Moses beseeches hashem, 515 times, to enter Eretz yisroel. (Vaetchanan is the numerical value 515)
What was Moses' supplication? Hashem helped me to understand, the word Leimor in the first sentence refers to the two following sentences which were repeated 515 times
To repeat two sentences 515 times one must dance and sing them.
Afterwards I saw the Bal Haturim who says the numerical value of Vaetchanan is the same numerical value as Shirah (song)..