Moed Katan 13A

צרם אזן בכור קנסו בנו אחריו ⁠— משום דאיסורא דאורייתא,

in the case of one who slit the ear of a firstborn animal, the rabbis penalized his son after him, that is because the prohibition is by Torah law. A firstborn animal is disqualified from sacrifice if it becomes blemished, rendering it permitted to be eaten as non-sacred meat. It is prohibited to deliberately engender a blemish in a firstborn animal, and one who does so is prohibited from eating the meat.

ואם תמצי לומר מכר עבדו לגוי ומת קנסו בנו אחריו ⁠— משום דכל יומא מפקע ליה ממצות,

And if you might say that in the case of one who sold his slave to a non-Jew and then died the rabbis penalized his son after him, that is because every day the slave is in the non-Jew’s possession precludes him from performing mitzvot. A Canaanite slave is obligated in the same mitzvot as a Jewish woman. If he is illicitly sold to a non-Jew and escapes, requiring the seller to compensate the non-Jew, the seller may not then re-enslave the slave, who is regarded as emancipated. The rabbis extended this penalty to the owner’s heirs as well.

הכא מאי: גברא קניס רבנן ⁠— והא ליתיה, או דלמא: ממונא קניס רבנן ⁠— והא איתיה!

What, then, is the halakha here, where one planned from the outset to perform his work on the intermediate days of a Festival and then after performing the work he died? Should one say that the rabbis penalized the man himself and he is no longer alive, or perhaps the rabbis imposed a penalty on the money, such that no benefit may be derived from it, and it still exists in the hands of his heirs?

אמר ליה, תניתוה: שדה שנתקווצה בשביעית ⁠— תזרע למוצאי שביעית, נטייבה או נדיירה ⁠— לא תזרע למוצאי שביעית. ואמר רבי יוסי בר חנינא: נקטינן, הטיבה ומת ⁠— בנו זורעה, אלמא: לדידיה קנסו רבנן, לבריה לא קנסו רבנן. הכא נמי: לדידיה קנסו רבנן, לבריה לא קנסו רבנן.

R' Zeira said to R' Yirmeya: You already learned the answer to your question in a Mishnah (Shevi’it 4:2): A field whose thorns were removed during the Sabbatical Year may be sown in the 8th year, as removing thorns is not full-fledged labor that renders the field prohibited; but if it had been improved with fertilizer, or if it had been enclosed so that animals therein would fertilize it with their manure, it may not be sown in the 8th year. The rabbis imposed a penalty that one not benefit from prohibited labor. And R' Yosei bar Ḥanina said: We have a tradition that if one improved his field in a prohibited manner and then died, his son may sow it. Apparently, the rabbis penalized only him, the one who acted wrongly, but the rabbis did not penalize his son. Here, too, with regard to work performed on the intermediate days of a Festival, the rabbis penalized him, but the rabbis did not penalize his son.