Ketubot, Chapter Nine, Mishnah Four
We learned in Shevuot 7:8: And these take an oath though there is no [definite] claim: partners, tenants, guardians, the wife who transacts the affairs in the house, and the son of the house. In other words in these cases one person can make another person swear an oath that he has not misused any of his property. Our mishnah further clarifies when a husband can make his wife take an oath.
A wifes managing her husbands affairs would not have been uncommon in Mishnaic society, especially if many of the men were merchants. Merchants are often away from home for long periods and while they are gone, it is typically the woman who manages the affairs of the houses.
1) If a husband set up his wife as a shopkeeper or appointed her guardian he may impose upon her an oath whenever he wants.
2) Rabbi Eliezer said: even in respect of her spindle and her dough.
Section one: If a husband appointed his wife to sell his produce in a store or to otherwise be a guardian over his property, he may at any time he wishes make her swear an oath that she has not acted improperly with his property. This is not because women are inherently not trustworthy, but rather because a person in such a situation may take certain licenses with property that is not his/hers. The fact that the husband, or in cases of partnership a partner, can make the other party take an oath, would probably have acted as a deterrent, preventing the person managing the funds from acting wrongly. Unfortunately, the problem of people taking license with money or property which they have been appointed to guard over, is still a major problem in our society.
According to the Talmud, a husband who did not appoint his wife as a shopkeeper or guardian cannot make her swear an oath over normal things that happen in the house. Allowing him to do so, and to be so tight-fisted with his property, would not help peace reign over their house.
Section two: This last point is disputed by Rabbi Eliezer. He holds that a husband can make his wife take an oath that she did not take for personal use any of the wool that he provided for her spindle nor from the dough that she uses for baking. Rabbi Eliezer evidently does not think that this will lead to a disruption of the household harmony, or he does not care.