Gregory the Dialogist

And that Thou shouldest visit him in the dawn, and try him suddenly? Which is there of us that does not know that it is called the 'dawn,' when the night season is now changing into the brightness of light? so we too are closed in by the darkness of night, when we are dimmed by the practice of wickedness; but the night is turned into light, when the darkness of our erring state is illuminated by knowledge of the Truth. …

Morals on the Book of Job, Book VIII ↗

Thomas Aquinas

He shows how God turns his heart towards him when he says, "You visit him at dawn," i.e. from the day of his birth you help him by your providence with things necessary for his life and glorification, whether they are corporeal or spiritual. "And immediately test him," by adversities in which he shows clearly he is disposed to virtue. …

Commentary on Job ↗