2,804. Vowing Not to Benefit From Water or Sailors

Hilchos Nedarim 9:18

If someone vows not to benefit from the water that flows from a certain spring, he is also prohibited all the rivers that are fed from it. It should go without saying that this means those that flow directly from this source. Even though the name changes and we call it “river X” or “well Y,” without any reference to the spring that was the subject of his vow, since the spring is the source for these bodies of water, he may not benefit from any of them. However, if someone vows not to benefit from river A or spring B, he is only prohibited those that are referred to by that name.

Hilchos Nedarim 9:19

If someone vows not to benefit from sea-faring people, he may benefit from those who live on land. If he vows not to benefit from those who live on land, he may not benefit from sea-faring people even if they put out to the Mediterranean because sea-faring people are considered as being among those who live on land. If he vows not to benefit from those who see the sun, he may not benefit from blind people because his intention was people who are seen by the sun. If he vows not to benefit from dark-haired people, he may not benefit from bald men or the white-haired, but he may benefit from women and children. If the local practice is to refer to everyone as dark-haired, then he may not benefit from anyone.