Siman 329

One who receives a field from his fellow and the receiver dies, leaving a son, the son cannot compel the lessor to leave the field in his hand until the time that was set with his father, for he can say: "To your father I desired to give the field, but to you I will not give," as is the case with all partners, as I have written in siman 176. And they appraise what the father did, and he pays this to the son. Even if he stipulated with him for a fixed time, the owner of the field cannot say, "Since he did not finish by the time, I will give nothing." And even to compel the son to finish the work is not within his power, for a worker may retract even in the middle of the day, and certainly this one, since he died and is under duress, that he pays the heirs for what he did. Even when he made a contract and a kinyan, they do not appraise what the surplus of the work would yield, even in a matter of loss, since he is under duress, as I have written in siman 333.

And if he already received during his lifetime his entire payment and died in the middle of the work, he should not say to the son: "Give me what your father received beyond what was due to him until the day of his death," for the son does not need to pay this even if his father left an inheritance. And there is one from whose words it appears that this is specifically when the owner of the field does not want to allow the son to finish the work, and therefore the son can say: "I will not return anything to you, but rather I will finish the work, and if you do not desire this, I am not obligated to return it to you." But if his desire is to leave the completion of the work in the hand of the son and the son does not want to finish, he is obligated to return the surplus of what his father received [so it appears from the Sma]. But I have not seen any of the poskim say so. For behold, he is not a robber such that the sons would be obligated to pay when he left property, as is written in siman 361. And behold, he is a worker, and our teacher, the Rema, ruled in siman 333 that a worker who received wages more than what he performed until now and became ill, since he already received it, he does not need to return it. However, even in this there are those who disagree, as is written there, and according to this opinion, it is certainly so: that if he wants to leave the completion of the work in the hand of the son and the son does not want to, if the father left property, the son is obligated to pay the surplus.