Morning — Didst thou create the sun, and appoint the order and succession of day and night. Since — Since thou wast born: this work was done long before thou wast born. To know — To observe the punctual time when, and the point of the heavens where it should arise; which varies every day.
Related Commentaries of Job 38:12
Job 38:12
12 Hast thou commanded the morning since thy days; and caused the dayspring to know his place;