Shabbos, Chapter 1, Mishnah 5. This mishnah presents a dispute between Beis Shammai and Beis Hillel that will serve as a central theme throughout the rest of the chapter: whether a person is commanded regarding the resting of his utensils on Shabbos.
The basis of the dispute - shevisas keilim (the resting of utensils):
Beis Shammai hold that a person is warned and commanded regarding the resting of his utensils. Not only is the person himself commanded to rest, and not only is his animal commanded to rest, but even the utensils and objects that he owns may not perform work on Shabbos - and this is so even when the Jew is not causing the work and is not performing it himself on Shabbos.
Our mishnah deals with the melachah of losh (kneading). This melachah does not refer specifically to kneading dough, but also to soaking items in a way that creates a thick mixture.
The words of the mishnah:
"Beis Shammai omrim: ein shorin dyo v'samemanin v'chirshinin ela k'dei sheyishoru mib'od yom" - three items are listed here, and all of them require soaking as part of their preparation:
Dyo - the materials that are mixed together in the preparation of ink.
Samemanin - the materials that are mixed together in the preparation of dyes.
Kirshinin - a type of animal feed.
In the opinion of Beis Shammai, one may soak them on Erev Shabbos only if there is enough time for the soaking to be completed while it is still day, before Shabbos begins. For if the process of soaking continues into Shabbos - and it is a form of kneading and mixing - a person is commanded to make sure that this does not take place with objects that he owns.
"u'Beis Hillel matirin" - Beis Hillel permit this, for although a person is commanded not to perform work himself, and is also commanded to make sure that his animal does not perform work for him, he is not commanded regarding his objects. Things that happen on their own, after he began them on Erev Shabbos, are permitted in their view.
In summary: in this mishnah Beis Shammai and Beis Hillel disagree about the question of the resting of utensils. In the opinion of Beis Shammai, one may soak ink, dyes and kirshinin only if their soaking will be completed while it is still day, whereas Beis Hillel permit it, since a person is not commanded regarding the resting of his objects.