Kerisus5: 2
רַבִּי עֲקִיבָא מְחַיֵּב עַל סְפֵק מְעִילוֹת אָשָׁם תָּלוּי, וַחֲכָמִים פּוֹטְרִים. וּמוֹדֶה רַבִּי עֲקִיבָא, שֶׁאֵין מֵבִיא אֶת־מְעִילָתוֹ עַד שֶׁתִּתְוַדַּע לוֹ, וְיָבִיא עִמָּהּ אָשָׁם וַדַּאי. אָמַר רַבִּי טַרְפוֹן: מַה לָּזֶה מֵבִיא שְׁתֵּי אֲשָׁמוֹת? אֶלָּא, יָבִיא מְעִילָה וְחֻמְשָׁהּ, וְיָבִיא אָשָׁם בִּשְׁנֵי סְלָעִים וְיֹאמַר: ,,אִם וַדַּאי מָעַלְתִּי, זוֹ מְעִילָתִי וְזֶה אֲשָׁמִי“; וְאִם סָפֵק, הַמָּעוֹת נְדָבָה וְאָשָׁם תָּלוּי, שֶׁמִּמִּין שֶׁהוּא מֵבִיא עַל־הוֹדַע, מֵבִיא עַל־לֹא הוֹדַע.
R’          Akiva holds [one] liable to an asham talui for a doubtful case of me’ilah, but the Sages exempt [him]. R’ Akiva agrees, however, that he does not bring his restitution until it becomes known to him, and he [then] accompanies it with the unconditional asham. Said R’ Tarfon: Why should this [person] bring two ashamos? Rather, let him bring restitution and its fifth, and let him bring an asham for two selaim and say, ‘‘If I am surely guilty of me’ilah, let this be my restitution and this my asham’’; and if it is doubtful, the money is a donation and the asham is an asham talui, for, from the [same] species from which he brings for an obligation of doubt, he brings for an obligation of certainty.
Kerisus5: 3
אָמַר לוֹ רַבִּי עֲקִיבָא: נִרְאִים דְּבָרֶיךָ בִּמְעִילָה מְעוּטָה. הֲרֵי שֶׁבָּא עַל־יָדוֹ סְפֵק מְעִילָה בְּמֵאָה מָנֶה, לֹא יָפֶה לוֹ שֶׁיָּבִיא אָשָׁם בִּשְׁתֵּי סְלָעִים וְאַל יָבִיא סְפֵק מְעִילָה בְּמֵאָה מָנֶה? הָא מוֹדֶה רַבִּי עֲקִיבָא לְרַבִּי טַרְפוֹן בִּמְעִילָה מוּעֶטֶת. הָאִשָּׁה שֶׁהֵבִיאָה חַטַּאת הָעוֹף סָפֵק: אִם עַד שֶׁלֹּא נִמְלְקָה נוֹדַע לָהּ שֶׁיָּלְדָה וַדַּאי, תַּעֲשֶׂנָּה וַדַּאי, שֶׁמִּמִּין שֶׁהִיא מְבִיאָה עַל לֹא הוֹדַע, מְבִיאָה עַל הוֹדַע.
Replied R’ Akiva to him: Your words are acceptable in the case of a small me’ilah. [But] what if he is guilty of a doubtful case of me’ilah of one hundred maneh, is it not better for him that he bring an asham for two selaim and not bring a doubtful restitution of one hundred maneh? R’ Akiva [then] agrees with R’ Tarfon in the case of a small me’ilah. [If] a woman brought a bird chatas of doubt: If it became known to her before its neck was nipped that she had definitely given birth, she must make it an unconditional [chatas], for, from the [same] species from which she brings for an obligation of doubt, she brings for an obligation of certainty.