The holy Ohr HaChaim revealed that five miracles are hinted at in this verse, and thus are his words: "It is a night of vigil" etc. — the verse intends to hint at five wondrous miracles that occurred on this night.

1. In the days of Avraham when he struck the four kings: "And he divided himself against them by night" (Bereishis 14:15).

2. During the Exodus from Egypt, as it is written (29): "And it came to pass at midnight."

3. In the days of Chizkiyahu, when Gavriel struck the camp of Sennacherib, as it is written (Melachim II 19:35): "And it came to pass that night."

4. In the days of Mordechai and Esther: "On that night the king’s sleep was disturbed" (Esther 6:1).

5. The future redemption.

The Ohr HaChaim explains from which words in the verse each of these five miracles is hinted at:

Corresponding to the miracle of Avraham, it says, "It is a night of vigil for Hashem," because through this miracle, His truth was revealed, as our sages said (Bereishis Rabbah, Parsha 42, Siman 7) that there were nations that did not believe in the miracle of his rescue from the furnace of Kasdim, and believed in the miracle of striking the four kings.

Corresponding to Egypt, it says, "to bring them out of the land of Egypt."

Corresponding to the miracle of Chizkiyahu, it says, "It is that night" — known to you, as recorded in the words of the prophet: "And it came to pass that night that an angel went out" etc.

Corresponding to the miracle of Mordechai, it says, "this night for Hashem."

And corresponding to the future redemption, it says, "a vigil for all the children of Israel throughout their generations," meaning at the end of days, speedily and in our time, amen.

The main idea that several miracles are hinted at here, the Ohr HaChaim likely derived from the fact that it is written "vigils" in the plural form, and not in the singular form "vigil."