Dalek and River in “The Big Bang”

You will be exterminated!

Not yet. Your systems are still restoring, which means your shield density is compromised. One alpha-meson burst through your eye stalk would kill you stone dead.

Records indicate you will show mercy. You are an associate of the Doctor.

I'm River Song. Check your records again. [points her gun at the Dalek]

[uneasily] Mercy.

[menacingly sweet] Say it again.

Mercy!

One more time.

Mercy!