Responsa על בבא מציעא 152:17

A - (1) Insofar as A is required to pay the scribe only for work that had been completed by the latter, the former may abrogate the agreement, even if the scribe is unable to procure other employment. However if people, who possess similar means as A, commission scribes to undertake such projects, then A can no longer assert, that due to financial circumstances, he must now cancel the agreement.

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.

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.