It's not a sutra, it's a way of chanting nembutsu. I've heard that the Jodo sect is “namu amidabu” and the Jodo Shinshu is “nanmanda.” However, my place is the Jodo sect, and it's usually “namu amidabu,” but since it's the Genji sect, they teach dance nenbutsu, and at that time it's basically “nanmanda.” baby talk? Namana means worshiping the Buddha, and it is said that it is filled with “nanmandamanda.” I don't really understand why there are differences in how to chant Nembutsu. Did you find it helpful?
appending
I see, the mystery of tuna manda has been solved. What a bunch of buttonotsu, isn't it?
It's pretty common in China, isn't it? Certainly.