2,750. Expanding a Vow

Hilchos Nedarim 3:3

“One is liable for expanding an existing vow” means that if one person heard another take a vow and he immediately said, “And I’m like you,” he is prohibited in the same thing as his fellow. If a third person heard the second’s response and he says, “I’m like you,” he is likewise prohibited. Even if 100 people each say, “I’m like you” immediately after one another, they all become prohibited.

Hilchos Nedarim 3:4

Similarly, if a person says, “This meat is prohibited to me,” and even several days later he says, “This bread is like this meat,” the bread likewise becomes prohibited. If he later says, “This honey is like this bread” and “This wine is like this honey” – even if he names 100 different things, they all become prohibited.