1. Rava: If a borrower admits that he wrote a loan document, it requires verification.
2. A sample can be considered a significant amount.
3. Ingredients of a sample are not always considered significant in order to make one liable for carrying on Shabbos.
4. There is a dispute among the Tana'im about whether Tefilin straps cause Tum'ah for Terumah.
5. One cannot make a Mezuzah out of a Sefer Torah or out of Tefilin that are worn out.
A BIT MORE
1. It is like a regular loan document, which a borrower can claim is forged, and thus Beis Din must verify that the signatures of the witnesses are authentic. This applies in a case where the borrower says that he has paid the loan, since he can claim that "just as you know the document is authentic only because of my word, you should also take my word that I have paid back this loan."
2. The Mishnah later states that an amount generally used for a sample of dye is enough to be liable for carrying on Shabbos.
3. Rav Nachman: This is why the Mishnah later (89b) requires a larger amount of ingredients than that needed for a sample of dye in order to be liable for carrying. A person does not prepare a sample of dye alone without preparing a whole pot of dye.
4. For example, the Tana Kama in the Beraisa maintains that Tefilin straps cause Tum'ah for Terumah when they are attached to Tefilin.
5. This is because of the rule that we only ascend in Kedushah and do not descend. A Sefer Torah and Tefilin are holier than a Mezuzah.