Talmud for Zevachim 157:1

“Hillel the elder used to make a sandwich of all three together⁵²Also quoted in the Babli, Pesaḥim 115a, Zebaḥim 79a. It is written about the Passover sacrifice (Ex. 12:8): “They shall eat the meat in that night, roasted on the fire, and maẓẓot, on bitter herbs they shall eat it.” Similarly, it says about the second Passover (Num. 9:11): “They shall eat it on maẓẓot and bitter herbs.” Hillel held that this means one has to eat of meat, maẓẓah, and bitter herbs together in one bite..” Rebbi Joḥanan said, they disagreed with Hillel the elder⁵³The Babli, Pesaḥim 115a, explains R. Joḥanan to say that in Temple times, when all three commandments are biblical, one has the choice to follow Hillel or eat the three ingredients separately. This cannot be the position of the Yerushalmi since then the discussion would not even start.. But did not Rebbi Joḥanan make a sandwich of maẓẓah and bitter herbs⁵⁴In the Babli, Rav Ashi (who lived after the compilation of the Yerushalmi) rules that one eats twice, once each item singly and once as a sandwich. Naturally, there cannot be any meat mentioned here; cf. the author’s The Scholar’s Haggadah (Northvale NJ, 1995) pp. 332–338. Since R. Joḥanan here is accused of inconsistency, he cannot have followed the custom established by Rav Ashi.? There in Temple times, here not in Temple times⁵⁵In the absence of a Temple, only maẓẓah is a biblical commandment since it is prescribed separately from any Temple service, Ex. 13:6–7. Bitter herbs are mentioned only as accessory to the sacrifice; therefore, today one eats bitter herbs purely as a remembrance of the Temple as rabbinical ordinance. R. Joḥanan must hold that a rabbinic ordinance cannot interfere with a biblical commandment. Therefore, it is possible to eat maẓẓah and bitter herbs together. But he holds that in Temple times, each of the three ingredients must be recognized by its taste. This position is the opposite of that of the Babli.. Even if you say here and there in Temple times, two kinds are more than the third and cancel it.⁵⁶This explains the rejection of Hillel’s position in Temple times. Since there are three biblical obligations, they cancel one another and none of them is fulfilled. Rebbi Yose in the name of Rebbi Eleazar⁵⁷Babli Zebaḥim 79a. R. Eleazar supports R. Joḥanan’s position against R. Simeon ben Laqish and his making a sandwich in the manner of Hillel. He must hold that R. Joḥanan reports that most authorities of Hillel’s time disagreed but he himself agrees.: Just as forbidden things do not cancel one another, so commanded things do not cancel one another.