Shevuos 2:5-3:1

רַבִּי אֱלִיעֶזֶר אוֹמֵר, הַשֶּׁרֶץ וְגוֹ’ וְנֶעְלַם מִמֶּנּוּ (ויקרא ה), עַל הֶעְלֵם שֶׁרֶץ חַיָּב, וְאֵינוֹ חַיָּב עַל הֶעְלֵם מִקְדָּשׁ. רַבִּי עֲקִיבָא אוֹמֵר, וְנֶעְלַם מִמֶּנּוּ וְהוּא טָמֵא (שם), עַל הֶעְלֵם טֻמְאָה חַיָּב, וְאֵינוֹ חַיָּב עַל הֶעְלֵם מִקְדָּשׁ. רַבִּי יִשְׁמָעֵאל אוֹמֵר, וְנֶעְלַם וְנֶעְלַם שְׁתֵּי פְעָמִים, לְחַיֵּב עַל הֶעְלֵם טֻמְאָה וְעַל הֶעְלֵם מִקְדָּשׁ: Rabbi Eliezer says: With regard to the sliding-scale offering the verse states: “Or if a person touches any impure thing, whether it is the carcass of a non-kosher undomesticated animal, or the carcass of a non-kosher domesticated animal, or the carcass of a non-kosher creeping animal, and it is hidden from him” (Leviticus 5:2). A precise reading of this verse indicates that in a case where one has a lapse of awareness that he had contracted ritual impurity by touching a creeping animal, he is liable to bring a sliding-scale offering for having defiled the Temple or the sacrificial food, but he is not liable to bring such an offering in a case where he has a lapse of awareness that he is entering the Temple or partaking of sacrificial food. Similarly, Rabbi Akiva says: The verse states: “And it is hidden from him, so that he is impure” (Leviticus 5:2), thereby teaching that in a case when one has a lapse of awareness that he had contracted ritual impurity, he is liable to bring a sliding-scale offering, but one is not liable to bring such an offering in a case when he has a lapse of awareness that he is entering the Temple or partaking of sacrificial food. Rabbi Yishmael says: The verse states: “And it is hidden from him” (Leviticus 5:2), and it states: “And it is hidden from him” (Leviticus 5:3), twice, in order to render one liable to bring a sliding-scale offering both in a case where one has a lapse of awareness that he had contracted ritual impurity and in a case where one has a lapse of awareness that he is entering the Temple.Mishnah Shevuot 2:5

שְׁבוּעוֹת שְׁתַּיִם שֶׁהֵן אַרְבַּע, שְׁבוּעָה שֶׁאֹכַל וְשֶׁלֹּא אֹכַל, שֶׁאָכַלְתִּי וְשֶׁלֹּא אָכַלְתִּי. שְׁבוּעָה שֶׁלֹּא אֹכַל וְאָכַל כָּל שֶׁהוּא, חַיָּב, דִּבְרֵי רַבִּי עֲקִיבָא. אָמְרוּ לוֹ לְרַבִּי עֲקִיבָא, הֵיכָן מָצִינוּ בְּאוֹכֵל כָּל שֶׁהוּא שֶׁהוּא חַיָּב, שֶׁזֶּה חַיָּב. אָמַר לָהֶן רַבִּי עֲקִיבָא, וְכִי הֵיכָן מָצִינוּ בִּמְדַבֵּר וּמֵבִיא קָרְבָּן, שֶׁזֶּה מְדַבֵּר וּמֵבִיא קָרְבָּן. שְׁבוּעָה שֶׁלֹּא אֹכַל וְאָכַל וְשָׁתָה, אֵינוֹ חַיָּב אֶלָּא אַחַת. שְׁבוּעָה שֶׁלֹּא אֹכַל וְשֶׁלֹּא אֶשְׁתֶּה וְאָכַל וְשָׁתָה, חַיָּב שְׁתָּיִם: With regard to oaths attesting to the truth about an utterance, which, when violated, render one liable to bring a sliding-scale offering, there are two types that are actually four types. The initial two oaths, which relate to utterances about the future and are explicitly prohibited in the Torah, are: On my oath I will eat, or: On my oath I will not eat. These are expanded to four, to include oaths concerning utterances about the past: On my oath I ate, or: On my oath I did not eat. If one says: On my oath I will not eat, and he then ate any amount, even less than an olive-bulk, he is liable; this is the statement of Rabbi Akiva. The Rabbis said to Rabbi Akiva: Where do we find that one who eats any amount is liable, leading you to say that this person is liable? Rabbi Akiva said to them: And where do we find one who speaks and is liable to bring an offering for it, as this oath taker merely speaks, i.e., takes an oath, and brings an offering for it? If one said: On my oath I will not eat, and then he ate and drank, he is liable to bring only one offering, because an oath to refrain from eating includes refraining from drinking. If he said: On my oath I will not eat and I will not drink, and then he ate and drank, he is liable to bring two offerings.Mishnah Shevuot 3:1