Genesis 1:8 KJV
And God called the firmament Heaven. And the evening and the morning were the second day.
Genesis 1:7 KJV
And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so.
Genesis 1:6 KJV
And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.