Actually, "Let there be light" is merely a paraphrase of the actual statement.

The complete text is not currently accessible, but artifacts are being studied to attempt it's reconstruction from the oldest surviving material.

The most commonly cited fragments generally accepted to have survived in form representing the actual statement are summarized at:

Abridged Transcript of the "Light" speech

Note that some of the "words" used in this transcript are not readily pronounced by persons not immersed in the study of the history and meaning of the statement.

John