Midrash sa Mga Awit 104:20: Ein Yaakov (Glick Edition) & Mekhilta DeRabbi Yishmael

(Ib. b) R. Zera lectured; according to others, R. Joseph taught: What is the meaning of the passage (Ib., ib. 20) Thou causest darkness and it becometh night, wherein creep forth all the beasts of the forest? Thou causest darkness, refers to this world which is compared to the darkness of night; wherein creep forth all the beasts of the forest, refers to the wicked that exist in this world, who are compared to wild beasts. The sun ariseth, they slink away and lie down in their den; the sun ariseth, for the righteous; they slink away, refers to the wicked who will go to Gehenna; and lie down in their den, refers to the upright, for there will not be an upright who will not have a dwelling in the world to come, according to his honor. Man goeth forth unto his work, refers to the upright who are going to receive their reward; and to his labor until the evening, [refers to him] who has completed his work [while alive] until the day of death.

And thus do you find with the forefathers, that they deported themselves with circumspection (in this regard), viz.: (Genesis 22:3) "And Abraham arose early in the morning," (Ibid. 28:18) "And Jacob arose early in the morning," (Exodus 34:4) "And Moses arose early in the morning," (I Samuel 15:12) "And Samuel arose early in the morning to meet Saul." Now does this not follow a fortiori, viz.: If the fathers and the prophets, who were on the way to do the will of Him who spoke and brought the world into being, conducted themselves with such circumspection, how much more so (should) others (do so)! And thus is it written (of this natural order) ((Psalms 104:20-21) "You bring on darkness and it becomes night. In it stir all the beasts of the forest. The lions roar for prey, etc." (28) "You give it (food) to them and they gather it in, etc." — (22) "When the sun rises, they return" (to their lairs) — after which (23) "Man goes out to his work, to his labor, until the evening."