Shevuos 7:8-8:1

Shevuos 7:8

The following take oaths even when no claim is made against them: business partners, sharecroppers, trustees, a wife who manages the home’s business and a son of the house (who manages the brothers’ inheritance). If one of these people is asked by an interested party to take an oath, he must do so. After partners or sharecroppers have divided their portions, an oath may no longer be imposed. If the partner or sharecropper became obligated to take an oath in another case, then any other oath may be included. The sabbatical year cancels oaths (i.e., those that must be taken when one partially acknowledges a debt).

Shevuos 8:1

There are four types of guardians: an unpaid watchman, a borrower, a paid watchman and a renter. An unpaid watchman takes an oath in all cases (where he cannot return the thing he was guarding), a borrower pays in all cases, a paid watchman and a renter take an oath in case where an animal is injured, captured or dies, but he pays when it is lost or stolen.