Pesachim 84A

ולא מילה שלא בזמנה, הבאה מקל וחומר.

but not a circumcision that is not at its ideal time. If, for some reason, circumcision was not performed on the 8th day after birth, its performance at a later date does not override a Festival, because the obligation to perform the circumcision is not particular to that specific day. This needed to be emphasized. Otherwise, it would have come to be derived through an a fortiori inference that circumcision does override Shabbat and Festivals, based on the fact that it overrides the laws of tzara'at. Therefore, the Torah emphasized that circumcision performed later than the 8th day does not override Festivals.

רב אשי אמר: ״שבתון״ דיום טוב ⁠— עשה הוא, ואין עשה דוחה לא תעשה ועשה.

Rav Ashi said a different reason that the leftover Paschal lamb is not burned on the Festival: The obligation of solemn rest stated with regard to Festivals is a positive mitzva. Therefore, the halakhot of Festivals include both a positive mitzva to rest from performing prohibited labor and a prohibition to avoid such labor, and a positive mitzva such as burning leftover sacrificial meat does not override both a prohibition and a positive mitzva.

מתני׳ כל הנאכל בשור הגדול ⁠— יאכל בגדי הרך, וראשי כנפים והסחוסים.

Mishnah: Anything that is fit to be eaten in an adult ox, whose bones have fully hardened, may be eaten in a young kid. One may register for a Paschal offering in order to eat any of these parts, and eating any such part is considered a fulfillment of the mitzva to eat the Paschal lamb. However, any part of the animal that is inedible in an adult ox is not considered meat, even if it is soft enough to be eaten in a young kid. One may not register for a Paschal offering in order to eat one of these parts, and eating it is not a fulfillment of the mitzva to eat the Paschal lamb. And the soft ends of the ribs and the cartilage are soft enough to be considered edible and may therefore be eaten from the Paschal lamb.