But they fear that the spirits of the dead will come back to haunt them, so they keep all of the victims' scalps and they cast spells on them so they don't come back.
11 seconds sound clip from the Kung Fu from Beyond the Grave movie soundboard.
You can hear this line at 00:46:40 in the DVD version of the movie.
Quote context
[...]
- But then, I don't understand why they tore out the victims' hearts.
- All right. I'll tell you what I know.
- I see. I've heard about this, as well.
- You can't go now. Kam Tai Fu's men are looking for you.
- Let's wait until dark, and I'll show you the way.
[...]