I once heard a story that there was a certain (talmudic) rabbi who held that the halacha is a certain way with regard to produce from the field (when you can harvest it or something like that) but that the majority of the rabbis decided a different halacha with regard to this produce.
Then the rabbi was once walking in the field with his students and they plucked the produce (or something like that) in accordance with the teaching of this rabbi. But the rabbi critized the student that he should not follow his halacha, as the halacha goes according to the majority of the rabbis. And even though he disagrees with the decided halacha, we have to follow it for the sake of its authority.
What is the source of this story? (I think it is from the Talmud)