Genesis 1:6

1:6 God said, “Let there be an expanse in the midst of the waters and let it separate water from water.

Genesis 1:8

1:8 God called the expanse “sky.” There was evening, and there was morning, a second day.

Genesis 1:15

1:15 and let them serve as lights in the expanse of the sky to give light on the earth.” It was so.