Pesachim 88B

תקנתם את רבו, ואת עצמו לא תקנתם. לישא שפחה אינו יכול ⁠— שכבר חציו בן חורין, לישא בת חורין אינו יכול ⁠— שעדיין חציו עבד. יבטל, והלא לא נברא העולם אלא לפריה ורביה, שנאמר: ״לא תהו בראה (אלא) לשבת יצרה״. אלא, מפני תיקון העולם כופין את רבו ועושה אותו בן חורין, וכותב שטר על חצי דמיו.

You have remedied the situation of his master, who benefits fully from all his rights to the slave, but his own situation you have not remedied. How so? He is not able to marry a female slave, since half of him is already free, and a free Jew may not marry a Canaanite female slave. He is also not able to marry a free woman, since half of him is still a slave, and a Jewish woman may not marry a Canaanite slave. And if you say he should be idle and not marry, but is it not true that the world was created only for procreation, as it is stated: “He did not create it to be a waste; He formed it to be inhabited” (Isaiah 45:18)? Rather, for the improvement of the world we force his master to make him a free man, and the slave writes a bill accepting his responsibility to pay half his value to his master. This was the original version of the Mishnah.

וחזרו בית הילל להורות כבית שמאי.

The ultimate version of the Mishnah records the retraction of Beit Hillel: And Beit Hillel retracted its position and ruled like Beit Shammai.

מתני׳ האומר לעבדו צא ושחוט עלי את הפסח, שחט גדי ⁠— יאכל, שחט טלה ⁠— יאכל, שחט גדי וטלה ⁠— יאכל מן הראשון.

Mishnah: In the case of one who says to his slave: Go and slaughter the Paschal offering on my behalf, but does not specify which type of animal to slaughter, the halakha is as follows: If the slave slaughtered a kid, his master may eat it; if he slaughtered a lamb, his master may eat it. If the slave slaughtered both a kid and a lamb, his master should eat from the first one that was slaughtered; the second is invalid and should be burned.