daf bit: Nedarim 17

[cellio]

(Today's daf is 18.)

The g'mara discusses the case where someone swears to transgress the torah, such as "I swear not to sit in the sukkah". If he swears to transgress and does not follow through (e.g. he actually does sit in the sukkah), is he liable to punishment when he obeyed the torah? The g'mara says that oaths to do evil, like those to do good, apply only to something that is optional. In this case the one who swore is not punished for sitting in the sukkah (it wasn't a valid oath in the first place, so he couldn't violate it) -- but he is punished for swearing falsely. (The penalty for this is lashes.) (16b-17a)

Off hand I don't know the penalty for not sitting in the sukkah, nor whether it comes from heaven or from the beit din (court).