Charles Ellicott Commentary Job 38:21

"[Doubtless], thou knowest, for thou wast then born, And the number of thy days is great!" — Job 38:21 (ASV)

Do you know it? —It is better to read this verse without an interrogation, as sublime irony. “Doubtless you know all this, for you were born then, and the number of your days is so great!”