A woman awaiting a yavam —- whether one yavam or two yevamin —- R' Eliezer says: He may revoke [her nedarim]. R' Yehoshua says: [When she awaits] one, but not two. R' Akiva say: Neither [when she awaits] one, nor two. Said R' Eliezer: If he can revoke the nedarim of a wife whom he acquired on his own, surely he can revoke the nedarim of a wife acquired for him by Heaven! Said R' Akiva to him: No; if you said this for a woman he acquired on his own, [it is because] others have no rights to her; shall you say this for a woman acquired for him by Heaven, to whom others do have rights? Said R' Yehoshua to him: Akiva, your words [apply] when there are two yevamin; what do you answer when there is one yavam? He said to him: The yevamah is not as complete [a wife] to the yavam, as a betrothed woman is a complete [wife] to her husband.