The phrase "let there be light" (Genesis 1:3) is the delivery of God's light to the Earth. He creates the Sun and Moon and stars in Genesis 1:14 to 1:18 -- remember that The Bible is based on a geocentric theory of the universe.
Jewish answer
The light created on the first day was not the same as that of the sun. Rather, it was light that God created before the sun, and which emanated from a point in space without any physical source; like what we might term a "white hole."
Supposedly God said "Let there be light"
God said let there be light
[1] In the beginning God created the heaven and the earth.[2] And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters.[3] And God said, Let there be light: and there was light.[4] And God saw the light, that it was good: and God divided the light from the darkness. I hope this anwers your ?
14 According to the Bible, "And on the fourth day he created the sun, the moon and stars, and he set them in the vault of heaven to give light on earth to have charge over day and night and to separate light from darkness." Then God said, "Let lights appear in the sky to separate the day from the night. Let them mark off the seasons, days, and years. 15 Let these lights in the sky shine down on the earth." And that is what happened. 16 God made two great lights-the larger one to govern the day, and the smaller one to govern the night. He also made the stars. 17 God set these lights in the sky to light the earth, 18 to govern the day and night, and to separate the light from the darkness. And God saw that it was good. 19 And evening passed and morning came, marking the fourth day. So the sun, moon, and stars.
As this is a religious question, you should ask your rabbi, minister, or imam. There was no other light in the world. It says in the Bible that God said "Let there be Light" and there was light. Therefor God would not have to create something that was already there.
God said "Let there be light," and there it was.
14 According to The Bible, "And on the fourth day he created the sun, the moon and stars, and he set them in the vault of heaven to give light on earth to have charge over day and night and to separate light from darkness." Then God said, "Let lights appear in the sky to separate the day from the night. Let them mark off the seasons, days, and years. 15 Let these lights in the sky shine down on the earth." And that is what happened. 16 God made two great lights-the larger one to govern the day, and the smaller one to govern the night. He also made the stars. 17 God set these lights in the sky to light the earth, 18 to govern the day and night, and to separate the light from the darkness. And God saw that it was good. 19 And evening passed and morning came, marking the fourth day. So the sun, moon, and stars.
God commanded let there be light and there was light.
Genesis 1:3 God said, "Let there be light," and there was light
It collects light
Genesis 1:3
Let there be light