Genesis 6:15

and this is that which thou dost with it: three hundred cubits is the length of the ark, fifty cubits its breadth, and thirty cubits its height;

Genesis 7:20

fifteen cubits upwards have the waters become mighty, and the mountains are covered;

Deuteronomy 3:11

for only Og king of Bashan had been left of the remnant of the Rephaim; lo, his bedstead is a bedstead of iron; is it not in Rabbath of the sons of Ammon? nine cubits its length, and four cubits its breadth, by the cubit of a man.

Treasury of Scripture Knowledge

Summary

And this is the fashion which thou shalt make it of: The length of the ark shall be three hundred cubits, the breadth of it fifty cubits, and the height of it thirty cubits.

Bible References

Cubits

Genesis 7:20
fifteen cubits upwards have the waters become mighty, and the mountains are covered;
Deuteronomy 3:11
for only Og king of Bashan had been left of the remnant of the Rephaim; lo, his bedstead is a bedstead of iron; is it not in Rabbath of the sons of Ammon? nine cubits its length, and four cubits its breadth, by the cubit of a man.