2,625. An Oath of Deposit
Hilchos Shevuos 1:7
The fourth and final subcategory of an oath in vain is taking an oath about something that one can’t do, such as not to sleep for three straight days and nights, not to eat for seven straight days, and similar things. If one makes an oath in vain through any of these four kinds, he violates a Torah prohibition, as per Exodus 20:7, “Do not take the name of Hashem your God in vain.” If one intentionally makes such an oath, he is liable to the penalty of lashes; if he does so unintentionally, he is exempt from punishment.
Hilchos Shevuos 1:8
An oath of deposit is when one person is in possession of money belonging to another, whether it was entrusted to him, a loan, if he stole it from him, if he withheld wages, if he found a lost item belonging to him and didn’t return it, or any comparable situation. If the other person demands his money and the first person denies having it, he violates a Torah prohibition, as per Leviticus 19:11, “You shall not deny...,” which refers to denying the possession of money; a person is not liable to lashes for such a violation. If a person takes a false oath about such a claim that he denied, then he violates another Torah prohibition, as the verse continues, “A man shall not lie to his fellow.” This refers to swearing when denying the money.