That you may know the power of the Lord, for seven days, Egypt will thirst.
7 seconds sound clip from the The Ten Commandments (1956) movie soundboard.
You can hear this line at 02:31:34.990 in the Blu-ray version of the movie.
Quote context
[...]
- We will learn if a god of shepherds is stronger than the gods of Pharaoh.
- Water of life, give drink to the desert, and make green the meadow.
- Aaron. Stretch out my staff against the waters.
- Look! There! Where he struck the river, it bleeds. The water turns to blood!
- That you may know the power of the Lord, for seven days, Egypt will thirst.
- Seven days without water! Fill every jug and jar!
- Pestilence will be everywhere!
- Were it seven times seven days, no magician's trick will set your people free.
- Sacred water, make pure the flood from which you came.
- And God smote the land with all manner of plagues, but still Pharaoh's heart was hardened.
[...]