Parashas Bo · Shemos 12:3 · TT note 3
Chabad.org — English translation + Rashi
Torah Temimah on Shemos 12:3, note 3 (on וְיִקְחוּ לָהֶם אִישׁ): a minor cannot acquire (for others) as an adult can.
Sefaria — Exodus 12:3
Sefaria — Torah Temimah on Exodus 12:3
English: “They shall take for themselves, each man, a lamb for a household” — Rabbi Yitzchak said: an adult acquires, and a minor does not acquire [on behalf of others in this way].
Derash on אִישׁ: capacity to take/acquire for the household is limited to one who is not a minor.
Although one person may take the Pesach for the household, the actor must be an adult; a minor cannot effect that acquisition for everyone.