Nedarim 28: vows to those who are undeserving

The rabbis address vows and oaths made to tax collectors or other unscrupulous people.  We can assume from their words that tax collectors are not necessarily scrupulous in their dealings.  They remind us that in a kingdom, we follow the laws of that kingdom.   However, tax collectors might not follow those laws themselves.

Beit Hillel and Beit Shammai discuss differences in how and whether laws or oaths might be used in such circumstances, of course where Beit Hillel's views are more lenient and Beit Shammai's views are more lenient.

We are introduced to the notion of the redemption of trees and clothing in a new Mishna.  A person might vow that his saplings are (like) and offering if they are not cut down/burned.  If no-one destroys his land, his trees/land is consecrated.  As well, if one says that these saplings are like an offering until they are cut down/burned, then they cannot be redeemed.  

The Gemara takes these statements and runs - it considers making vows on produce that does not belong to the house of the king.  It discusses more ideas about tax collection.  It speaks to extortionists who force people to take vows that disadvantage their wives and/or children.  As well, it speaks to the greater severity of oaths, which means that we must be more careful when we take oaths.  Beit Shammai do not even allow people to request the dissolution of oaths.