And God called the firmament Heaven. And the evening and the morning were the second day.
All Commentaries on Genesis 1:8 Go To Genesis 1
Ephrem The Syrian
AD 373
Although God said about the light that came to be on the first day that "it was very good," He did not say this about the firmament which came to be on the second day, because the firmament had not yet been finished, neither in its structure nor in its adornment. The Creator delayed until the lights came to be so that when [ the firmament ] was adorned with the sun and the moon and the stars, and the strength of the darkness that was weakened by the lights shining from it, He would then say of the firmament as well as of [ the rest of creation ] that "it was very good."