Mishnah Kerisos 3:7: Rabbi Akiva said: I asked Rabban Gamaliel and Rabbi Yehoshua at the meat-market of Emmaus where they went to buy beef for the wedding feast of Rabban Gamaliel's son: What [is the ruling if] one had relations with his sister, and his father's sister, and his mother's sister under one spell of unawareness? Is he liable for one [sacrifice] for all of them, or one [sacrifice each] for each of them? And they said to me: We have not heard [any teaching about this matter], but we have heard that if one had relations with his five wives who were Niddot under one spell of unawareness, he is liable for each [act], and it seems to us that [your case may be understood by employing] a fortiori reasoning.

אמר רבי עקיבא שאלתי את רבן גמליאל ואת רבי יהושע באטלס של אמאום שהלכו ליקח בהמה למשתה בנו של רבן גמליאל הבא על אחותו. ועל אחות אביו. ועל אחות אמו. בהעלם אחד. מהו. חייב אחת על כולן. או אחת על כל אחת ואחת. ואמרו לי לא שמענו. אבל שמענו הבא על חמש נשיו נדות. בהעלם אחד. שהוא חייב על כל אחת ואחת. ורואין אנו שהדברים קל וחומר:

Mishnah Kerisos 3:8: Rabbi Akiva further asked them: What [is the ruling regarding impurity] of a limb hanging loose from [the body of a living] animal? They said to him: We have not heard [any teaching about this matter], but we have heard that a limb hanging loose from [the body of] a man is pure. This is what one afflicted with boils would do in Jerusalem. On the eve of Pesach he would go to the doctor who would cut [the limb] until only a barley-corn [size of flesh] remained. He then stuck it on a thorn and tore himself away from it. Both he [the patient] and the doctor could [subsequently] bring their Passover offerings. And it seems to us that [your case may be understood by employing] a fortiori reasoning.

ועוד שאלן רבי עקיבא אבר המדולדל בבהמה מהו. אמרו לו לא שמענו אבל שמענו באבר המדולדל באדם שהוא טהור. שכך היו מוכי שחין בירושלים עושין. הולך לו ערב פסח אצל הרופא. וחותכו עד שהוא מניח בו כשעורה. ותוחבו בסירה. והוא נמשך ממנו. והלה עושה פסחו. והרופא עושה פסחו ורואין אנו שהדברים קל וחומר: