Nazir 31 - Mistakes
What if one said this, "The black ox, which will emerge out of my house first, shall be a sacrifice," - and instead a white ox comes out first? Will the white ox become a sacrifice?
Beit Shammai say that indeed it will. Why? Because Beit Shammai claim that consecrations, even done by mistake, are still valid. One cannot undo a consecration to the Temple if it was done by mistake. Another explanation is that he really made no mistake. He planned for the first ox to become sacred. To emphasize, he specified that it will be black (as this was more valuable to him). But even if a white one comes out first - it will become sacred, and the color does not matter.
Which reason is the real one? Do his mistakes become consecrations, or do we simply reinterpret his words to make sense? The Talmud tries to derive the answer from the rule above, but to every proof it finds an exception disproving it, thus the question remains unresolved - in this particular discussion.
Regardless, Beit Hillel state that his statement must agree precisely with the intended effect, and only then does his consecration become valid.
Art: Cart With Red And White Ox by Vincent Van Gogh