Pesachim 95B

מאי קא מרבה? ״אל תאכלו ממנו נא״. בפרטיה מאי קא ממעטי? ״לא תשחט על חמץ דם זבחי״. איפוך אנא! מצוה דגופיה עדיף.

what is it including, beyond what is mentioned explicitly in the verse? The Talmud answers that it includes the mitzva: “Do not eat from it raw” (Exodus 12:9). The Talmud asks: What does it exclude through its detail? The Talmud answers that it excludes the mitzva: “You should not offer the blood of My sacrifice with leavened bread” (Exodus 34:25). The Talmud asks: Perhaps I can reverse it and say the opposite, that the prohibition against eating the offering raw is excluded, and the prohibition against owning leaven is included. The Talmud answers: Including a mitzva related to the Paschal lamb itself is preferable to including one that does not relate as directly to the Paschal lamb. Therefore, the prohibition against eating the Paschal lamb raw is included, and the prohibition against slaughtering the Paschal lamb with leaven in one’s possession is excluded.

הראשון טעון הלל באכילתו וכו׳. מנא הני מילי? אמר רבי יוחנן משום רבי שמעון בן יהוצדק: אמר קרא ״השיר יהיה לכם כליל התקדש חג״. לילה המקודש לחג ⁠— טעון הלל, לילה שאין מקודש לחג ⁠— אין טעון הלל.

It was taught in the Mishnah that the Paschal lamb on the first Pesaḥ requires the recitation of hallel as it is eaten, whereas on the second Pesaḥ it does not. The Talmud asks: From where are these matters derived? R' Yoḥanan said, citing R' Shimon ben Yehotzadak, that the verse states: “You should have a song as in the night when a Festival is sanctified” (Isaiah 30:29). From here it may be derived that a night sanctified as a Festival, on which labor is prohibited, such as the first night of Passover, requires the recitation of hallel; however, a night which is not sanctified as a Festival, such as the night when the Paschal lamb is eaten following the second Pesaḥ, does not require the recitation of hallel.