Joshua 1:4

⁴ From the desert and from Libanus unto the great river Euphrates, all the land of the Hethites unto the great sea toward the going; down of the sun, shall be your border.

Euphrates

In Genesis 2:14 and Psalms 80:9, 10, the Euphrates symbolizes secular knowledge — facts — and the sensory impressions on which facts are based. (Secrets of Heaven 120)