2,635. An Oath Dependent on Another Person's Intentions

Hilchos Shevuos 2:14

If a person decided not to eat bread made from wheat but he verbalized an oath not to eat bread without specifying that detail, he may not eat wheat bread because bread without any qualification means wheat bread.

Hilchos Shevuos 2:15

If someone takes an oath not to eat on a certain day and he qualifies that his oath depends on a certain person’s intention, he can’t later object based on his own intentions. This is because his oath wasn’t dependent on his own intentions, but on those of the other person. Since his words agreed with the intentions of the person he specified, he is liable, their intentions operating in lieu of his own. The same applies to the other types of oaths.