Numbers 32:19

We will not take possession of any land on the other side of the Jordan River, to the west and beyond. We already have our land here, east of the Jordan.

Joshua 13:8

With whom the Reubenites and the Gadites have received their inheritance, which Moses gave them, beyond Jordan eastward, even as Moses the servant of Jehovah gave them.

Genesis 13:10-12

Lot looked up and saw that the district of the Jordan River was well watered, like the garden of Jehovah, like the land of Egypt, toward Zoar. This was before Jehovah destroyed Sodom and Gomorrah.

Genesis 14:12

They also captured Lot, son of Abram's brother, who lived in Sodom, and his goods, and departed.

Numbers 32:32-33

We will enter Canaan as armed troops in Jehovah's presence. The land we will take possession of is here, east of the Jordan.

Numbers 34:15

on the eastern side of the Jordan, opposite Jericho.

Joshua 1:14-15

Your wives, your little ones, and your cattle, shall remain in the land Moses gave you on this side of the Jordan. But you shall pass before your brothers armed, all the mighty men of valor, and help them.

Joshua 12:1-6

These are the kings of the land that the children of Israel defeated and who's territory they captured. It was on the other side of Jordan toward the rising of the sun, from the Arnon River to Mount Hermon, and all the plain on the east.

2 Kings 10:32-33

Jehovah began to reduce the size of Israel's territory. King Hazael of Syria conquered all the Israelite territory

2 Kings 15:29

In the days of Pekah king of Israel Tiglathpileser king of Assyria captured Ijon and Abelbethmaacah and Janoah and Kedesh and Hazor and Gilead and Galilee and all the land of Naphtali. He took the people captive to Assyria.

1 Chronicles 5:25-26

But they were unfaithful to the God of their fathers and prostituted themselves to the gods of the peoples of the land, whom God had destroyed before them.

Proverbs 20:21

An inheritance may be gotten hastily at the beginning; but in the end it will not be blessed.

Treasury of Scripture Knowledge

Summary

For we will not inherit with them on yonder side Jordan, or forward; because our inheritance is fallen to us on this side Jordan eastward.

Bible References

We will

Genesis 13:10
Lot looked up and saw that the district of the Jordan River was well watered, like the garden of Jehovah, like the land of Egypt, toward Zoar. This was before Jehovah destroyed Sodom and Gomorrah.
Genesis 14:12
They also captured Lot, son of Abram's brother, who lived in Sodom, and his goods, and departed.
2 Kings 10:32
Jehovah began to reduce the size of Israel's territory. King Hazael of Syria conquered all the Israelite territory
2 Kings 15:29
In the days of Pekah king of Israel Tiglathpileser king of Assyria captured Ijon and Abelbethmaacah and Janoah and Kedesh and Hazor and Gilead and Galilee and all the land of Naphtali. He took the people captive to Assyria.
1 Chronicles 5:25
But they were unfaithful to the God of their fathers and prostituted themselves to the gods of the peoples of the land, whom God had destroyed before them.
Proverbs 20:21
An inheritance may be gotten hastily at the beginning; but in the end it will not be blessed.

Because

Numbers 32:33
So Moses gave the tribes of Gad, Reuben, and half of the tribe of Manasseh, son of Joseph, the kingdoms of King Sihon of the Amorites and King Og of Bashan. It was the whole land with its cities and its surrounding territory.
Joshua 12:1
These are the kings of the land that the children of Israel defeated and who's territory they captured. It was on the other side of Jordan toward the rising of the sun, from the Arnon River to Mount Hermon, and all the plain on the east.
Joshua 13:8
With whom the Reubenites and the Gadites have received their inheritance, which Moses gave them, beyond Jordan eastward, even as Moses the servant of Jehovah gave them.