Deuteronomy 3:18

Then I gave them the following instructions: 'Jehovah our God gave you the land east of the Jordan to occupy. Now arm your fighting men and send them across the Jordan ahead of the other tribes of Israel, to help them occupy their land.

Joshua 4:12-13

The children of Reuben, and the children of Gad, and half the tribe of Manasseh, passed over armed before the children of Israel, as Moses spoke to them.

Numbers 32:20-24

Moses answered: If you really mean what you say, then here in the presence of Jehovah get ready to go into battle.

Joshua 1:12-15

And to the Reubenites, and to the Gadites, and to half the tribe of Manasseh, Joshua said:

Joshua 22:1-9

Joshua called together the people of the tribes of Reuben, Gad, and Manasseh.

Treasury of Scripture Knowledge

Summary

And I commanded you at that time, saying, The LORD your God hath given you this land to possess it: ye shall pass over armed before your brethren the children of Israel, all that are meet for the war.

General references

Bible References

I commanded

Numbers 32:20
Moses answered: If you really mean what you say, then here in the presence of Jehovah get ready to go into battle.
Joshua 1:12
And to the Reubenites, and to the Gadites, and to half the tribe of Manasseh, Joshua said:
Joshua 4:12
The children of Reuben, and the children of Gad, and half the tribe of Manasseh, passed over armed before the children of Israel, as Moses spoke to them.
Joshua 22:1
Joshua called together the people of the tribes of Reuben, Gad, and Manasseh.

General references

Numbers 32:17
Then we will be ready to march in battle formation ahead of the other Israelites until we have brought them to their land. Meanwhile our families will live in walled cities. They will be safe from the other people who live here.