Responsa for Bava Metzia 157:1

Q - A engaged B as a tutor, for a season. B refused to accept the position unless the entire salary would be paid in advance. A thereupon complied with B's request. At the beginning of the season, A died. Is B entitled to the complete salary?
A - B must return the money he received. He is not entitled to receive for the remaining time, even the wages paid an idle worker, since he encountered no loss.

Q. A, a widow's trustee, leased half of the widow's house, for a term of ten years, to C, who, in turn, leased it to B. After B moved into the house, A became greatly dissatisfied with him and demanded that B move out of the house immediately, on the ground that he had leased the house to C, and therefore was under no obligation to B. He told B, however, that should C have any claims against him on account of the eviction of B, he, A, would answer these charges in court. B, however, claimed: that C rented the house from A on condition that he (C) lease it to whomever he wants; that he, B, was willing to partition off the part of the house he occupies from the rest of the house; and that he would guarantee to pay the widow for any damages she may sustain as a result of his remaining on the premises. A, however, claimed that he feared that grave damages to the widow will result if B stays, and that the widow cannot dwell in one house with a snake (meaning B).
A. Since A admits that C had the right to lease the house to anyone he pleased, A cannot evict B from the widow's house.
SOURCES: Cr. 259; Pr. 680; Mord. B. M. 357; Agudah B. M. 125. Cf. Hag. Maim. to Sekirut 5, 20; Weil, Responsa 10.

Q. The community of T engaged A as cantor for a three years' period, but soon retracted, discharging A and hiring B in his place. Now A institutes suit against B.
Q. A has no legal claim against B though he does have a claim against the community. Not having been asked regarding A's case against the community, I shall refrain from passing judgment thereon. Should the discussion that follows reveal any just claims A may have against the community, I rely on you not to disclose them to A, lest the community accuse me of encouraging claimants and inciting them against the community thus damaging its interests. It seems, however, that if A could have obtained another position, had he not been engaged by the community of T, and now can no longer obtain that, or a similar, position, the community ought to pay A the wages of an "idle laborer" (i. e. the wages a cantor would be willing to accept for abstaining from practicing his profession for a given period). But, if A is able to obtain another position even now, he has no legal claim against the community, though he has cause for reproof. Should the latter position require more effort than the position with the community of T, if there be also an increase in remuneration commensurate with the increase in effort, the community of T would be free from obligation to A; otherwise, the community of T would have to compensate A for the increase in effort. In any event, A has no legal claim against B, though he has cause for reproof, and the latter may perhaps be called "wicked".
SOURCES: Cr. 292; Am II, 234; B. p. 298 no. 392.