2,654. An Oath of Expression With No Future Component

Hilchos Shevuos 4:22

Let’s say that one person tells another that he’s taking an oath not to eat in his home, or his friend was badgering him to eat in his home and he refuses, saying that an oath will take effect if he eats in the friend’s home, or that it won’t take effect if he doesn’t eat in his home. These statements create prohibitions tantamount to an oath not to eat in the friend’s home. If he said all of these things, after which he violated his words and ate in the friend’s house, he’s only liable once.

Hilchos Shevuos 5:1

Let’s say that someone took an oath that person X threw a stone into the sea but he didn’t actually do so, or he took an oath that person X didn’t throw the stone when he had. In such a case, one is liable for taking an oath of expression even though there’s no future component, i.e., a person can’t take an oath that a third party will throw or not throw something in the future. One who takes an oath about another person’s future actions isn’t liable for taking an oath of expression, even regarding his own son or wife. This is because it’s not in his control to keep or annul such an oath. One is given stripes for acting rebelliously for making an oath he cannot keep, which is an oath taken in vain.