Midrash su Giobbe 38:12

And God called the light day - Is it not day when there's light? This is surprising! It is taught: the light that was created in the six days of Creation cannot illuminate during the day because it dims the sun, and at night it cannot since it was only created to illuminate during the day. And where is it? It is hidden,and is prepared for the righteous for the Future, as it says "and the light of the moon will be like the light of the sun, and the light of the sun will be seven times like the light of the seven days" (Isaiah 30:26). This is surprising! Seven? Aren't they three (days)? Weren't the luminaries created on the fourth? Rather, it is like a person who says 'such and such way I order for the seven days of my wedding feast.' Rabbi Nechemiah said: these are the seven days of mourning for the righteous Metushelach, that the Holy One of Blessing gave to them light in abundance. 'And God saw that the light was good' - Rabbi Ze'ira the son of Rabbi Abahu explained in Cesarea: from where do we know that we do not say a blessing over the candle before its light is established? From here: and He saw; and He separated. Rabbi Yehudah in the name of Rabbi Simon said: He separated it for Himself. The rabbis say: He separated it for the righteous in the Future. This is similar to a king who had a beautiful meal and separated it for his son. Said Rabbi Berachiah: 'Rabbi Yochanan and Rabbi Shimeon ben Lakish, two great ones of the world, explained this: 'and He separated' is a complete separation. This is similar to a king who had two commanders, one to command during the day and one to command during the night, and the two were disputing with one another, one saying 'I command during the day' and the other saying 'I command during the day.' So the king called the first one and said: 'Ploni, the day will be your charge.' And so to the second and said: 'Ploni, the night will be your charge.' Said Rabbi Yochanan: 'This is what the Holy One of Blessing said to Job: "Have you commanded the morning since your days began, and caused the dawn to know its place?" (Job 38:12) Do you know your place? This is surprising. Said Rabbi Tanchuma: 'I will say its reason: "Fashioner of Light and Creator of Darkness, Maker of Peace" (Isaiah 45:7) From the moment of its creation, He makes peace. 'And God called the light day' - said Rabbi Eleazar: The Holy One of Blessing never unites His name to evil, only to goodness: it is not written 'and God called the light day; and the darkness God called night'; rather, [it is written] 'and the darkness, called night.'