Responsa for Bava Batra 306:2
אמר רב הונא בריה דרב יהושע כמאן אזלא הא שמעתא דרבה כר' נתן דתניא מי מוציא מיד מי הוא מוציא מידיהן בלא ראיה והן אין מוציאין מידו אלא בראיה דברי רבי יעקב
men and the restrictions of dead<span class="x" onmousemove="('comment',' If a priest who had married the daughter of an Israelite (and who had, thereby. conferred upon her the right of eating of the heave-offering) was among the passengers, it is assumed that he is dead, and his wife is henceforth deprived of the privilege he had conferred upon her (cf. Git. ibid.). ');"><sup>5</sup></span> men, how much more [ought we to do] so<span class="x" onmousemove="('comment',' To assume that the testator recovered from the illness during which be made the gift. ');"><sup>6</sup></span> [in the case of] sick men, of whom most do recover. R. Huna, the son of R. Joshua. said: In accordance with whose [view] may that reported statement of Rabbah be justified?<span class="x" onmousemove="('comment',' Lit., 'goes'. ');"><sup>7</sup></span>
Teshuvot Maharam
A. If A has now sufficient knowledge to teach B's son, the burden of proof lies on B that A did not have such knowledge at the time he was engaged. However, since B has one witness to support his claim, A must take an oath to the effect that he had sufficient knowledge at the time of the agreement. If A takes such oath, he will be entitled to collect his full wages from B.
SOURCES: Cr. 3; Pr. 488; Mord. B. B. 621. Cf. Agudah B. M. 172.