2,856. "I Didn't Know That a Nazir Couldn't..."
Hilchos Nezirus 1:14
If someone makes a nazirite vow and later claims that he didn’t know that a nazir was prohibited to drink wine, to be rendered unclean or to cut his hair, and that if he had known, he wouldn’t have made the vow, he is still a nazir and is bound by all these prohibitions. The reason is because he knew that at least one of these things would be prohibited and, as we have previously discussed, if one takes a vow prohibiting even one of these things, he is prohibited all of them.
Hilchos Nezirus 1:15
Let’s say that someone claims, “I know that a nazir is prohibited in all of these things, but I thought that I would be permitted to drink wine because I can’t live without wine,” or “…because I bury the dead.” In such a case, he is not rendered a nazir because his vow was a vow made in error. As previously discussed, such a vow need not be permitted by a Torah scholar.