Parashas Bo · Passuk 12:3
Chabad.org — English translation + Rashi
Torah Temimah points to Mechilta (verified).
Sefaria — Exodus 12:3
Sefaria — Mechilta
English: “For a father’s house” — “father’s house” means only a family, as it is said, “according to their families, by their fathers’ houses.”
In context: See the cited source for the full section.
Derash on the verse (Mekhilta) — not a formal named middah of the 13.
“Father’s house” denotes the family unit for joining in a Pesach.