Parashas Bo · Shemos 12:9 · TT note 9
Torah Temimah on Shemos 12:9, note 9 (on וּבָשֵׁל מְבֻשָּׁל בַּמָּיִם) points to Pesachim 41a.
Sefaria — Exodus 12:9
Sefaria — Torah Temimah on Exodus 12:9
Sefaria — Pesachim 41a
E-Daf — Pesachim 41a
English: Rabbi says: “In water” — I have only water; other liquids from where? Therefore it says “cooked thoroughly,” in any manner.
Kal vachomer / ribbui: if water (which does not dull taste) is forbidden, other liquids all the more so; the doubled wording covers all liquids.
Cooking the Pesach in any liquid, not only water, is forbidden.