Deuteronomy 1:7
6 The Lord our God spoke to us at Horeb and said, “You have stayed in the area of this mountain long enough. 7 Head out and resume your journey. Enter the Amorite hill country, and all its neighboring areas, including the rift valley, the hill country, the foothills, the Negev, and the coastal plain—all of Canaan and Lebanon as far as the Great River, that is, the Euphrates. 8 Look! I have already given the land to you. Go, occupy the territory that I, the Lord, promised to give to your ancestors Abraham, Isaac, and Jacob, and to their descendants.”
Revelation 9:14
13 Then the sixth angel blew his trumpet, and I heard a single voice coming from the horns on the golden altar that is before God, 14 saying to the sixth angel, the one holding the trumpet, “Set free the four angels who are bound at the great river Euphrates!” 15 Then the four angels who had been prepared for this hour, day, month, and year were set free to kill a third of humanity.
Notes and References
"... The Euphrates River, the largest river in the region—which, unlike most rivers in the Near East, was never known to dry up - formed the eastern boundary of the land promised in God’s covenant with Abraham and his seed (Genesis 15:18; Deuteronomy 1:7-8; Joshua 1:3-4). The heathen were thought to live outside the boundaries of this land. The action here reminds the reader of the drying up of the Red Sea in the Exodus from Egypt (Exodus 14:21) and the Jordan River in the conquest of Canaan (Joshua 3:7-17; see also 2 Kings 2:8). Israel’s scriptures expected the Exodus miracles to be repeated when the people returned from exile (Isaiah 11:15-16; Zechariah 10:10-12; 2 Esdras 13:39-47). The reason given for the drying of the Euphrates is to prepare the way for the kings from the East. Although Isaiah promised the waters would dry up for Israel’s return from Assyria (Isaiah 11:15-16), and Titus recruited from beyond the Euphrates for the Jewish War that culminated in the fall of Jerusalem in A.D. 70 (Ford, 1975:273), the most clear referent for the imagery in this passage is no doubt the expected return of Nero from the East ..."
Yeatts, John R. Revelation (p. 294) Herald Press, 2003