2,793. Inferring the Context of a Vow
Hilchos Nedarim 8:10
Similar to the previous halacha (about one’s intentions), if someone invited a friend for a meal and he responded by making an oath or a vow not to enter the host’s home or even to drink cold water from him, he may in fact enter his home and drink his water since his intention was only not to eat and drink with the host at the meal to which he was invited. The same is true in all comparable cases.
Hilchos Nedarim 8:11
Let’s say that one person makes a vow or an oath, telling another that he will never enter that person’s home or purchase his field, and that person subsequently dies or sells that field to a third party. In such a case, the one who vowed may enter that house or buy that field from the original owner’s heir or purchaser because his intention was only for while these things belonged to the now-deceased owner. However, if he said: “I will never enter this house” (as opposed to “your house”) or “I will never buy this field” (rather than “your field”), then even if the owner dies or sells the field to a third party, the one who vowed is prohibited.