Mishnayos Nedarim Perek 7 Mishnah 1

For one who vows that vegetables are forbidden to him, it is permitted for him to eat gourds, as people typically do not include gourds in the category of vegetables; and Rabbi Akiva prohibits him from eating gourds. The Rabbis said to Rabbi Akiva: But doesn’t a person say to his agent: Purchase vegetables for me, and the agent, after failing to find vegetables, returns with gourds and says: I found only gourds? This indicates that gourds are not considered vegetables. Rabbi Akiva said to them: The matter is so, and that proves my opinion; or perhaps, does the agent return and say: I found only legumes? Rather, it is apparent that gourds are included in the category of vegetables, although they differ from other vegetables, and therefore, the agent purchases gourds and explains that he found only gourds. And legumes are not included in the category of vegetables, and that is why the agent dispatched to purchase vegetables would not purchase legumes at all. And for one who vows that vegetables are forbidden to him, it is prohibited to eat the fresh cowpea, which is considered a vegetable, and it is permitted to eat dry cowpea, which is not a vegetable.

הַנּוֹדֵר מִן הַיָּרָק, מֻתָּר בִּדְלוּעִין. וְרַבִּי עֲקִיבָא אוֹסֵר. אָמְרוּ לוֹ לְרַבִּי עֲקִיבָא, וַהֲלֹא אוֹמֵר אָדָם לִשְׁלוּחוֹ קַח לִי יָרָק וְהוּא אוֹמֵר לֹא מָצָאתִי אֶלָּא דְלוּעִין. אָמַר לָהֶם, כֵּן הַדָּבָר, אוֹ שֶׁמָּא אוֹמֵר הוּא לוֹ לֹא מָצָאתִי אֶלָּא קִטְנִית, אֶלָּא שֶׁהַדְּלוּעִין בִּכְלָל יָרָק, וְקִטְנִית אֵינָן בִּכְלָל יָרָק. וְאָסוּר בְּפוֹל הַמִּצְרִי לַח, וּמֻתָּר בַּיָּבֵשׁ: