Contradiction with Genesis 15:18
This verse says that God gave the land from the river of Egypt to the Euphrates to Abram's descendants, which is a broader territory than described in Joshua 15:4.
Genesis 15:18: In the same day the LORD made a covenant with Abram, saying, Unto thy seed have I given this land, from the river of Egypt unto the great river, the river Euphrates:
Contradiction with Joshua 1:4
Here, God promises Joshua territory from the wilderness and Lebanon to the great river, the Euphrates, which expands far beyond the borders delineated in Joshua 15:4.
Joshua 1:4: From the wilderness and this Lebanon even unto the great river, the river Euphrates, all the land of the Hittites, and unto the great sea toward the going down of the sun, shall be your coast.
Contradiction with Numbers 34:5
This verse describes the southern border of the Promised Land as extending to the river of Egypt, which differs from the borders in Joshua 15:4.
Numbers 34:5: And the border shall fetch a compass from Azmon unto the river of Egypt, and the goings out of it shall be at the sea.
Contradiction with Genesis 13:14-15
God's promise to Abram includes "all the land that you see," suggesting a larger area than the specific boundary detailed in Joshua 15:4.
Genesis 13:14-15: And the LORD said unto Abram, after that Lot was separated from him, Lift up now thine eyes, and look from the place where thou art northward, and southward, and eastward, and westward: