What the inhabitants of these parts don't realize is that a vampire cannot cross a threshold unless he is invited by someone already inside. And if he is, all the garlic flowers in the world won't keep him out.

14 seconds sound clip from the Dracula: Prince of Darkness movie soundboard.

You can hear this line at 01:09:29.258 in the Blu-ray version of the movie.

Quote context

[...]

- Then, you and I will do what has to be done. We will pull that castle down stone by stone if necessary. We will find him wherever he is.

- I still don't see why we can't start immediately.

- No, it is better to wait until Mrs. Kent is safely away.

- Last night Dracula was robbed of his prey, your wife. He has seen her and touched her. He considers that she belongs to him already. He will want her badly.

- He won't come here?

- It is unlikely. And even if he does, he will not get in.

- What the inhabitants of these parts don't realize is that a vampire cannot cross a threshold unless he is invited by someone already inside. And if he is, all the garlic flowers in the world won't keep him out.

- Yes, master, yes.

- Oh, darling, I'm sorry, I didn't mean to wake you.

- Are you alright?

- Yes, of course.

- You're the one we have to worry about. The important thing is to get you well enough to go home.

[...]