When the Nile ran red, I too was afraid, until word came of a mountain beyond the cataracts which spewed red mud and poisoned the water.
11 seconds sound clip from the The Ten Commandments (1956) movie soundboard.
You can hear this line at 02:33:01.742 in the Blu-ray version of the movie.
Quote context
[...]
- Why do you bring this worker of evil before me?
- The people desert the temples. They turn from the gods.
- What gods? You prophets and priests made the gods, that you may prey upon the fears of men.
- Was it the staff I gave you that caused all this?
- Was it the wonder of your god that fish should die, and frogs should leave the waters?
- These things were ordered by themselves, not by any god! Now, go.
[...]