Genesis 1:8 KJV
And God called the firmament Heaven. And the evening and the morning were the second day.
Genesis 1:6–10 KJV Chapter Context
6
And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.
7
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.
8
And God called the firmament Heaven. And the evening and the morning were the second day.
9
And God said, Let the waters under the heaven be gathered together unto one place, and let the dry land appear: and it was so.
10
And God called the dry land Earth; and the gathering together of the waters called he Seas: and God saw that it was good.