Numbers 2:10

On the south side the armies led by Reuben will camp under their flag. The leader for the people of Reuben is Elizur, son of Shedeur

Numbers 1:5

Here are the names of the men who will help you: Elizur, son of Shedeur, from the tribe of Reuben,

Genesis 49:3-4

Reuben, you are my firstborn; you are my strength and the first child of my manhood. You are the proudest and strongest of all my sons.

Numbers 7:30

On the fourth day the leader of the descendants of Reuben, Elizur, son of Shedeur,

Numbers 7:35

and two bulls, five rams, five male goats, and five one-year-old male lambs as a fellowship offering. These were the gifts from Elizur, son of Shedeur.

Numbers 10:18

Next, the banner of the division led by the tribe of Reuben would start out, company by company. Elizur son of Shedeur was in command.

1 Chronicles 5:1

The sons of Reuben the firstborn of Israel he was the firstborn, but when he defiled his father's marriage bed, his rights as firstborn were given to the sons of Joseph son of Israel; so he could not be listed in the genealogical record in accordance with his birthright,

Treasury of Scripture Knowledge

Summary

On the south side shall be the standard of the camp of Reuben according to their armies: and the captain of the children of Reuben shall be Elizur the son of Shedeur.

Bible References

Camp of reuben

Genesis 49:3
Reuben, you are my firstborn; you are my strength and the first child of my manhood. You are the proudest and strongest of all my sons.
1 Chronicles 5:1
The sons of Reuben the firstborn of Israel he was the firstborn, but when he defiled his father's marriage bed, his rights as firstborn were given to the sons of Joseph son of Israel; so he could not be listed in the genealogical record in accordance with his birthright,

Elizur

Numbers 1:5
Here are the names of the men who will help you: Elizur, son of Shedeur, from the tribe of Reuben,
Numbers 7:30
On the fourth day the leader of the descendants of Reuben, Elizur, son of Shedeur,
Numbers 10:18
Next, the banner of the division led by the tribe of Reuben would start out, company by company. Elizur son of Shedeur was in command.

General references

Numbers 1:20
The roster of families and households for the descendants of Reuben, Israel's firstborn son, listed every man by name that was at least twenty years old and eligible for military duty.
Numbers 3:29
The families descended from Kohath put up their tents on the south side of the tent of meeting.
Numbers 7:30
On the fourth day the leader of the descendants of Reuben, Elizur, son of Shedeur,