R' Eliezer also said: They can find grounds to annul a neder on the basis of an unexpected development; the Sages, however, prohibit it. How? [If] he said: “Konam, my having benefit from So-and-so,” and he became a scribe, or was shortly to marry off his son, and he said: “If I had known that he would become a scribe, or that he was about to marry off his son, I would not have made the neder!”; [or if one said:] “Konam, this house, with respect to my entering [it],” and it was made into a synagogue, [and] he said: “If I had known that it would be made into a synagogue, I would not have made the neder!” —- R' Eliezer permits it; the Sages, however, forbid it.