God called the light Day, and the darkness He called Night. So the evening and the morning were the first day.
Genesis 1:5
Surrounding context
1:4 And God saw the light, that it was good; and God divided the light from the darkness.
1:5 God called the light Day, and the darkness He called Night. So the evening and the morning were the first day.
1:6 Then God said, "Let there be a firmament in the midst of the waters, and let it divide the waters from the waters."