Gregory the Dialogist

He hath set a time to darkness, and Himself vieweth the end of all and everyone. He hath Himself 'set a time to the darkness,' i.e. bounds to the wicked, where they should cease to be wicked. Whence it is said to them by the Apostle; Ye were sometimes darkness, but now are ye light in the Lord. Like as to the other disciples as well the same great teacher saith, The night is far spent, the day is at hand; let us therefore put off the works of darkness, and let us put on the armour of light. Let us walk honestly as in the day. …

Morals on the Book of Job, Book XVIII ↗

Thomas Aquinas

He then proceeds to examine other things which have a determined time and place from divine disposition and so are subject to divine knowledge. The greater part of these are hidden from men. The darkness of night hides the sun and many other things from us, but this happens by divine disposition, and so he says, "He placed a time for the darkness." Also, some things are hidden from us by their corruption when they are resolved into their principles, which are known to God but hidden from us, and so he says, "and he considers the end …

Commentary on Job ↗