“Mantras are strange; watching (kanju) excludes ignorance (mumyo).
Senri is included in one character, and I immediately testify that it is a law.”
This is an explanation of Odaishi (Kobo Daishi Kukai)'s work, “The Secret Key to the Heart Sutra.”
If I were to briefly translate it into modern language
Mantras (Buddha's words) are strange things.
If you imagine the Buddha or the Buddha's world in your heart, it will dispel your doubts, as if illuminating the darkness.
It contains many truths in just one letter, and it is possible to reach the state of a Buddha while remaining in this living body.
The effects of mantras do not fade over time, but I think your feelings when reciting mantras may still fade or change over time.
So, please sing it every once in a while.
Just because you bite or make a mistake doesn't mean misfortune will happen.
However, if it bites you a lot, don't panic and chant it slowly and carefully.
Also, please feel the Buddha's world through mantras, get rid of your doubts, and spend your days peacefully and better with a sense of gratitude.
I hope it's helpful.
Gassho (^ people ^)