Yevamot

[If a woman said to her husband]. 'Konam,  I do aught for your mouth',  he  need not annul [her vow].  R. Akiba, however, said: He  must annul it, since she might do more [work] than is due  to him!  Surely in connection with this it was stated: R. Huna son of R. Joshua said, [This law  applies only] where she said, 'My hands  shall be consecrated to Him who made them', since her hands are in existence. This  differs [from the opinion] of R. Nahman b. Isaac. For R. Nahman b. Isaac stated: R. Huna [holds the same opinion] as Rab,  Rab as R. Jannai, R. Jannai as R. Hiyya. R. Hiyya as Rabbi,  Rabbi as R. Meir, R. Meir as R. Eliezer b. Jacob. and R. Eliezer b. Jacob as R. Akiba, who stated that a man may transfer possession of a thing that is not yet in existence. What statement is it [that records the opinion of] R. Huna? It was stated: He who sold the fruit of a date-tree  to another may. said R. Huna, withdraw from the sale before they come into existence; but after they have come into existence he may no longer withdraw.  R. Nahman, however, stated: He may withdraw even after they have come Into existence.  Said R. Nahman: I admit, that if he  had already plucked and ate them, [compensation] is not to he extracted from him. As to Rab?  — [In that] which R. Huna stated in the name of Rab: If a man said to another, 'let this field which I am about to buy be yours as from now the moment I buy it', [the latter] acquires It. 'R. Jannai [is of the same opinion] as R. Hiyya'; for R. Jannai had a tenant  who used to bring him a basket of fruit every Sabbath Eve. Once as it was growing dark, and [the tenant] did not come, [R. Jannai] took  tithe  from the fruit which [he had] at home for [the redemption of] those.  When he subsequently came before R. Hiyya [the latter] said to him, 'You have acted well; for it was taught: That thou mayest learn to fear the Lord thy God always  refers to Sabbaths and festivals'.  Now, in 'respect of what law?  If in respect of giving tithe  so that one may be allowed to eat,  was it necessary [it may be asked] for a Scriptural text to permit moving,  [the prohibition of which is only] Rabbinical!