If your rabbi accidentally tells you that something is allowed, and you follow him, are you punished?

Question

Imagine that you're 119 years old.

You ask your rabbi whether or not something is allowed. He answers. But, unbenownst to you, his answer is 100% mistaken. The Talmud and all others agree unanimously that the thing is forbidden. But your rabbi misremembers what it says in the Talmud, and he says it is allowed.

For the next two years, you do the thing, thinking it's allowed.

On your 121st birthday, while doing the thing, you suddenly die instantly. Not due to doing the thing: just due to old age. You die without having said the deathbed confessional prayer (see the "Death and Bereavement" section of the ArtScroll Siddur).

Will G-d punish you for having done the thing?

_{(This question was inspired by a discussion between Akiva Miller and R' Yosef Gavriel Bechhofer.)}

Answer 1

No. A person who does something forbidden without any intention or knowledge of the sin is not held liable. This is a principle that appears several times in the Gemara.

For example, in Kritot 19a, there is an argument between R. Eliezer and Yehoshua about a person's liability in various transgressions. The Gemara teaches that R. Eliezer always finds the person accountable, where as R. Yehoshua responds:

אמר לו רבי יהושע: הרי הוא אומר אשר חטא בה, עד שיודע לו במה חטא. ורבי אליעזר האי בה מאי עביד ליה? מיבעי ליה: פרט למתעסק.

R. Yehoshua replied: It says "Wherein he has sinned" [as previously discussed, the word wherein - asher - from Lev. 4:23 alludes to the intention of an action]. It must be known to him wherein he sinned. And for what does R. Eliezer employ the word "wherein"? - To exclude unpurposed action.

The Gemara continues discussing the possible exceptions to this rule, where a person acting without knowledge of the sin is still liable because one receives pleasure from the sin (i.e., eating helev, committing incest). There is also a discussion about whether violating Shabbat would also be an exception of holding one liable, even if done unintentionally.

So the answer depends on what exactly this old man did (he must be in pretty good shape if he passes Moshe Rabbeinu's age!). If the sin didn't involve an enjoyment of bodily pleasure and it didn't involve violating Shabbat, then it appears that he will not be held liable for what he did.