Genesis 1:18

to preside over the day and the night, and to separate the light from the darkness. ¹  God saw that it was good.

Ps 19:6; Jer 31:35

¹ sn In days one to three there is a naming by God; in days five and six there is a blessing by God. But on day four there is neither. It could be a mere stylistic variation. But it could also be a deliberate design to avoid naming “sun” and “moon” or promoting them beyond what they are, things that God made to serve in his creation.