Parashas Bo · Shemos 12:4 · TT note 11
Torah Temimah on Shemos 12:4, note 11 (on אִישׁ לְפִי אׇכְלוֹ תָּכֹסּוּ) points to Sukkah 42b.
Sefaria — Exodus 12:4
Sefaria — Torah Temimah on Exodus 12:4
Sefaria — Sukkah 42b
E-Daf — Sukkah 42b
English: [A minor] who can eat an olive’s bulk of roast meat — one may slaughter the Pesach on his behalf, as it is said, “each according to what he eats.” Rabbi Yehudah says: until he can distinguish food. How so? They give him a pebble — and he throws it away; a nut — and he takes it.
Derash of לְפִי אׇכְלוֹ: capacity to eat a kezayis of roast is the threshold for a minor’s enrollment.
A child able to eat a kezayis of roast may have the Pesach slaughtered for him and be counted in the group.