Parashas Bo · Passuk 11:4
Chabad.org — English translation + Rashi
Torah Temimah points to Berachos 3b (verified).
Sefaria — Exodus 11:4
Sefaria — Berachos 3b
E-Daf — Berachos 3b
English: “Around midnight” — it is written kachatzot. Is there uncertainty before Heaven? Rav Ashi said: It was at the midpoint of the night of the thirteenth leading into the fourteenth. And thus Moshe said to Yisrael: The Holy One, blessed be He, said, “Tomorrow, around midnight as it is now, I will go out into the midst of Egypt.”
On the daf / in context: See the cited source for the full section.
Derash on the verse (Bavli sugya) — not a formal named middah of the 13.
There is no uncertainty before Heaven about the exact moment of midnight; Moshe’s wording reflects the timing of the announcement relative to the coming night.