7718. 'For three days' means a complete state, as just above in 7715.

Egyptians represent people who are in natural knowledge. In contrast, the Hebrews, people who are of the church, represent people in spiritual knowledge. The Egyptians also held the Hebrews to be so vile, as servants, that it was an abomination to them to eat with the Hebrews (Genesis 43:32), and also the sacrifices offered by the Hebrews were an abomination to them. (Exodus 8:26)

(Reference: Arcana Coelestia 5013)