Why don't you teach him one of your secret Kung Fu techniques instead? I'm sure you do know the fatal fist!
9 seconds sound clip from the Drunken Arts & Crippled Fist movie soundboard.
You can hear this line at 00:42:21 in the DVD version of the movie.
Quote context
[...]
- That's why he taught me all he knows so I'd have all I need.
- Old master, at least teach him some new techniques so he can handle Chow when next they meet.
- No, I won't. Chow Tai Hi was once a pupil of mine too.
- And Tai Hi has more experience, that's true. It's not easy, no.
- You can't do that to him. I hope you're not gonna cripple him. That would be awful!
- So that's why I can't teach him that.
- Old master, you're the boss here. You can always change the rules anytime you want.
- No, I can't. I can't betray my ancestors.
[...]