Talmud for Shabbat 279:4

אתמר ר"א אמר אחד זה ואחד זה אסור ורבי יוחנן אמר אחד זה ואחד זה מותר אביי ורבא דאמרי תרוייהו אין הלכה כרבי יוחנן

Said Samuel to him: 'By hand'! Does one then crush it every day by hand — is it asses' food? Rather said Samuel: He must crush it by hand, but not with a utensil. It was stated, R. Eleazar said: Both the one and the other are forbidden; while R. Johanan ruled: Both the one and the other are permitted. Abaye and Raba both say: The <i>halachah</i> is not as R. Johanan. R. Johanan [subsequently] adopted R. Eleazar's thesis, while R. Eleazar adopted Samuel's thesis. Abaye and Raba both said [then]: The <i>halachah</i> is as R. Johanan.

Jerusalem Talmud Shabbat