Numbers 2:10

On the south side shall be the standard of the camp of Reuben, according to their armies; the ruler of the sons of Reuben shall be Elizur the son of Shedeur.

Numbers 1:5

And these are the names of the men that shall stand with you: of Reuben, Elizur, the son of Shedeur;

Genesis 49:3-4

Reuben, you are my first-born, my might, and the beginning of my strength, the excellency of dignity and the excellency of power.

Numbers 7:30

On the fourth day Elizur the son of Shedeur, ruler of the sons of Reuben, offered.

Numbers 7:35

and for a sacrifice of peace offerings, two oxen, five rams, five male goats, five lambs of the first year. This was the offering of Elizur the son of Shedeur.

Numbers 10:18

And the standard of the camp of Reuben pulled up according to their armies. And over his army was Elizur the son of Shedeur.

1 Chronicles 5:1

And the sons of Reuben, the first-born of Israel (for he was the first-born; but since he defiled his father's bed, his birthright was given to the sons of Joseph the son of Israel, and the genealogy is not to be counted according to the 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 first-born, my might, and the beginning of my strength, the excellency of dignity and the excellency of power.
1 Chronicles 5:1
And the sons of Reuben, the first-born of Israel (for he was the first-born; but since he defiled his father's bed, his birthright was given to the sons of Joseph the son of Israel, and the genealogy is not to be counted according to the birthright;

Elizur

Numbers 1:5
And these are the names of the men that shall stand with you: of Reuben, Elizur, the son of Shedeur;
Numbers 7:30
On the fourth day Elizur the son of Shedeur, ruler of the sons of Reuben, offered.
Numbers 10:18
And the standard of the camp of Reuben pulled up according to their armies. And over his army was Elizur the son of Shedeur.

General references

Numbers 1:20
And the sons of Reuben, Israel's first-born son, by their generations, according to their families, by their fathers' house, according to the number of the names, by their heads, every male from twenty years old and upward, all that were able to go forth to war:
Numbers 3:29
The families of the sons of Kohath shall pitch on the side of the tabernacle southward.
Numbers 7:30
On the fourth day Elizur the son of Shedeur, ruler of the sons of Reuben, offered.