You must not use your kung fu so freely, not unless it's vital. It's too powerful.

9 seconds sound clip from the Of Cooks And Kung Fu (1979) movie soundboard.

You can hear this line at 01:20:00 in the Blu-ray version of the movie.

Quote context

[...]

- Grandpa, you feeling better now?

- Yes, thank you.

- It will take some time for my wound to heal.

- You must be good and practice.

- I will, you better rest now. I'll go and practice.

- Grandpa! Grandpa you shouldn't be up yet.

- It's alright.

- Has your kung fu improved?

- It has. My kung fu's much better. I've invented a new technique using the killer's style and mine together. It's so powerful, you watch.

- You must not use your kung fu so freely, not unless it's vital. It's too powerful.

- Grandpa, how are you feeling now?

- Not too bad.

- Grandpa, can you tell me why the man with the hat wants to kill you so badly, and why did he kill uncle too?

- Do you think he's the one that killed my parents?

- Yes, I do.

- Why is that?

- Well, son, the wound on your uncle's neck is identical to the one that killed your parents.

[...]