Here are 5 Bible verses about firmament from the Old and New Testaments of the Holy Bible (King James Version), sorted from most to least relevant.
Daniel 12:3 KJV
And they that be wise shall shine as the brightness of the firmament; and they that turn many to righteousness as the stars for ever and ever.
Genesis 1:14 KJV
And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years:
Psalms 19:1 KJV
The heavens declare the glory of God; and the firmament sheweth his handywork.
Psalms 104:2 KJV
Who coverest thyself with light as with a garment: who stretchest out the heavens like a curtain:
Genesis 1:8 KJV
And God called the firmament Heaven. And the evening and the morning were the second day.