2,769. The Products of Vow-Prohibited Produce

Hilchos Nedarim 5:13

If someone declares, “This produce is to me like an offering,” “to my mouth an offering” or “on my mouth an offering,” he may not eat anything that was exchanged for it or that grows from it. He may certainly not consume their juice.

Hilchos Nedarim 5:14

Let’s say that someone took a vow or an oath not to eat or to taste produce. If it’s something whose seed decomposes when planted, like wheat and barley, he may eat the things exchanged for it and that grow from it. If it was something whose seed doesn’t decompose when planted, like onions and garlic, then even the things that grow from the things that grow from it are prohibited. In any event, there is a doubt regarding their juices. Accordingly, if he drinks them, he is not liable to the penalty of lashes.