Eliphaz, like Job (Job 23:12), was aware that God had revealed his divine laws to men, even though they were unacquainted with the Mosaic laws, given later at Sinai.

Source:

KJV Defenders Study Bible, by Dr. Henry Morris, Ph.D.
Publisher: Thomas Nelson
Language: English
DEF 10 ISBN 0-529-10444-x
DEF 10-1 ISBN 0-529-10445-8