Parashas Bo · Passuk 12:5
Chabad.org — English translation + Rashi
Torah Temimah points to Mechilta (verified).
Sefaria — Exodus 12:5
Sefaria — Mechilta
English: “A perfect male lamb (seh)” — seh includes a kid and a lamb. “Perfect” — to exclude one with a blemish. “Male” — to exclude a tumtum, an androgynos, and a female.
In context: See the cited source for the full section.
Derash on the verse (Mekhilta) — not a formal named middah of the 13.
The Pesach must be an unblemished male from the sheep or goats.