Rabbi Elazar ben HaKafar, a) in the chapter "All Idols" [(M.G. 1, and P.D. Avot Rabbi Elazar HaKafar). And it seems to me that it should be Rabbi Elazar HaKafar (and this is a place name, and he and his son, who is called Bar Kafra, are buried there, thus wrote the Gaon of Israel. And I do not understand how his son is called Bar Kafra).
In the Jerusalem Talmud, in the first chapter of Beitzah, law 3, this is one of the four things that Rabbi Chiya said have no answer, and Rabbi Elazar, son of Rabbi Elazar HaKafar, answered (and in the Babylonian Talmud, Chulin [4:2], Rabbi Elazar HaKafar answered in the presence of Rabbi) what if circumcision, etc., and so it is in the Tosefta, first chapter of Beitzah (see above, Abba Arikha) and in the sixth chapter of Chulin, Rabbi Elazar HaKafar said, "Great is peace," etc. Rabbi Elazar, son of Rabbi Elazar (and in Yalkut Nasa, the words "Rabbi Elazar ben" are omitted) HaKafar says, "Great is peace," etc. (Sifrei, Parashat Nasa, "May HaShem lift His countenance upon you").
In the fifth chapter of Ketubot, in the Tosefta, Rabbi Menachem ben Nafach said in the name of Rabbi Elazar HaKafar, "There was an incident with Rabbi Tarfon who betrothed seven women to feed them terumah in a year of drought," and in Perek Acharon [(N.6 b)] Rabbi Yochanan said that he sent a hen before Rabbi Elazar HaKafar in the presence of Rabbi [(see there)] Rabbi Yochanan said, "Once I followed Rabbi Elazar HaKafar in the presence of Rabbi" [(Avodah Zarah 3 b) and in Taanit (11 a) it is taught that Rabbi Elazar HaKafar in the presence of Rabbi said, "Rashi explained in the presence of Rabbi, meaning a great person, and thus they call him by this title (see above, in the presence of Rabbi) and in Nazir (19 a) regarding one who has sinned against the soul, Rabbi Elazar HaKafar in the presence of Rabbi said. And in Nedarim (10 a) and Bava Kamma (21 b)].
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