Genesis 6:15

And this which thou shalt make it, three hundred cubits the length of the ark; fifty cubits its breadth, and thirty cubits its height

Genesis 7:20

Fifteen cubits from upward, the waters prevailed: and will cover the mountains.

Deuteronomy 3:11

For only Og, king Of Bashan, remained from the remnant of the Rephaims; behold, his bed, a bed of iron; is it not in Rabbath of the sons of Ammon? nine cubits its length and four cubits its breadth, according to 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 from upward, the waters prevailed: and will cover the mountains.
Deuteronomy 3:11
For only Og, king Of Bashan, remained from the remnant of the Rephaims; behold, his bed, a bed of iron; is it not in Rabbath of the sons of Ammon? nine cubits its length and four cubits its breadth, according to the cubit of a man.