Or HaChaim on Exodus 12:30/אור החיים על שמות י״ב:ל׳

1 ויקם פרעה לילה, Pharaoh rose up during the night, etc. The reason that the Torah mentions "at night," something that was obvious, is that according to the Zohar 2, page 38 that night was as bright as daylight. I have already found an allusion to this fact in Exodus 13,8 where the Torah instructs the Jewish father to tell his sons about the happenings during that night ביום ההוא, "on that day." The Torah means that the father should not fail to mention that one of the things that occurred during that night was that the night turned into day. In the event that we would think that the daylight during that night shone for both the Egyptians and the Israelites, the Torah emphasises that when Pharaoh rose he thought it was night because for him it was dark.