1 Chronicles 5:9

And eastward he inhabited unto the entering in of the wilderness from the river Euphrates: because their cattle were multiplied in the land of Gilead.

Cross-reference

1 Chronicles 5:16 describes the Gadites' territory in Gilead, paralleling the Reubenite settlement in the same region here.

Genesis 15:18 promises Abraham the land to the Euphrates; here Reuben's territory reaches that same river, echoing the promised boundary.

Joshua 1:4 Allusion

In Joshua 1:4, the Euphrates is promised as a boundary; here the Reubenites occupy that territory, fulfilling the land promise.