A river flowed out of Eden to water the garden, and there it divided and became four rivers. - Genesis 2:10
The Euphrates is one of the rivers that flowed out of Eden. (Genesis 2:10, 2:14)
When defining the land promised to Abram and his offspring, the Lord said, “To your offspring I give this land, from the river of Egypt to the great river, the river Euphrates, the land of the Kenites, the Kenizzites, the Kadmonites, the Hittites, the Perizzites, the Rephaim, the Amorites, the Canaanites, the Girgashites and the Jebusites.” (Genesis 15:18-21)
David caught the king of Zobah at the Euphrates
After receiving the Davidic covenant, the LORD gave victory to David wherever he went. David defeated Hadadezer the son of Rehob, king of Zobah, as he went to restore his power at the river Euphrates. (2 Samuel 8:3-8)
Ahijah's prophesy against Jeroboam's sin
Ahijah the prophet prophesied that Israel would be rooted out of their good land and scattered beyond the Euphrates because of the sins of Jeroboam. (1 Kings 14:15-16)
Pharoah Neco's camp
Pharaoh Neco, king of Egypt's army was at the river Euphrates at Carchemish. (Jeremiah 46:2)