Pesachim 9:8-9
Pesachim 9:8
If an animal intended for a Passover offering got mixed up with animals intended for other sacrifices, they must all be left to graze until they develop a disqualifying blemish. When this happens, the animals are sold and he must bring a sacrifice of each kind involved for the value that the most expensive animal brought (because we don’t know for which sacrifice the best animal was intended). Since he’s spending the value of the largest sale on each type of sacrifice, he’ll be spending more than he made by selling these animals; he must make up the difference from his own money. If the animal for the Passover offering was confused with firstborn animals, Rabbi Shimon says that if the party that signed up for this Passover offering was a group of kohanim (priests), they must eat all of the animals involved on seder night.
Pesachim 9:9
Let’s say that a group lost the animal intended for their Passover offering and they told one of the group to go find it and slaughter it, and he did, but in the meantime they bought and slaughtered a substitute animal. If he slaughtered his first, he eats his and they must join him. If theirs was slaughtered first, they eat theirs and he eats his. If it is unclear which was slaughtered first, or if both were slaughtered at the same time, he eats his and they may not join him. Theirs must be burned but they need not offer again on second Passover (Pesach sheini). If he told the others, “If I delay, go slaughter the Passover offering for me” and then he went, found the missing animal and slaughtered it, and they meanwhile bought and slaughtered a different animal, then if theirs was slaughtered first, they eat from theirs and he must join them. If his was slaughtered first, he eats his and they eat theirs. If it is unclear which was slaughtered first, or if both were slaughtered at the same time, they eat theirs and he may not join them. His must be burned but he need not offer again on second Passover. If he told them to slaughter for him if he is delayed and they told him to find and slaughter the lost animal, they must all eat from whichever animal was slaughtered first. If it is unclear which was slaughtered first, both animals must be burned. If neither he nor they gave any instructions to the other, nobody is responsible for anybody else (and therefore everyone eats from their own offering).