Or HaChaim on Exodus 12:42/אור החיים על שמות י״ב:מ״ב

1 ליל שמורים הוא לה׳ It was a night of vigil for G׳d, etc. The verse refers specifically to those miracles G'd performed at night. 1) In the days of Abraham when the latter defeated the four kings with his 318 men at night (Genesis 14,15); 2) during the Exodus when G'd is reported to have killed the firstborn at midnight (12,29). 3) In the days of Hezekiah when the angel Gabriel smote the army of Sancheriv on that night (Kings II 19,35). 4) In the days of Mordechai and Esther when the king could not sleep (Esther 6,1). 5) The redemption of the Jewish people in the future.

2Concerning the miracle in Abraham's time, the Torah says here "it was a night of vigilance for G'd," because G'd had demonstrated His truth as mentioned in Bereshit Rabbah 42. According to the Midrash there were some people who did not believe that G'd had saved Abraham from Nimrod's furnace in Ur Kasdim at the time. When they heard about how Abraham defeated these four kings, they changed their minds. The verse goes on to say "to take them out of Egypt," a reference to what happened during this night; the words הוא הלילה, are an allusion to the night in the future when G'd would smite the army of Sancheriv. The allusion to what would happen in the time of Mordechai and Esther is contained in the words הזה לה׳, whereas the reference to the redemption of the future is provided by the words שמורים לכל בני ישראל לדרותם, i.e. at the end of the exiles, may it happen soon.