The theme of today’s daf (Nedarim 64a) is התרת נדרים, meaning ‘the annulment of vows’, with our Mishna (Nedarim 9:1) specifically focusing on the various situations that would justify the annulment of a vow.
Interestingly, the Mishna uses the word פתח, meaning ‘opening’, to describe the justification given to annul a vow, and it describes a variety of ‘openings’ which may be accessed to annul a vow such as a change in circumstances which then prompts the person who made the vow to say, ‘if only I’d have know then what I know now, I would not have made my vow’.
Given all this, we may naturally think that the word פתח refers to the search and discovery of a viable halachic entry-point to a vow in order to annul it – just like one tries to find an open door to enter a seemingly locked building. Accordingly, the פתח is what is being sought by the Sage to annul the vow of the person who approached them for התרת נדרים.
But there is another way of understanding the word פתח which, as Rabbi Samson Raphael Hirsch explains, not only describes doors that we can enter, but also traps that we can fall into. According to this approach, the process of התרת נדרים begins with the person who made the vow thinking about the trap that they fell into by committing themselves to something which they now have come to regret. Thus, rather than being the פתח which is used to release the person, this פתח is recognized as being the trap that ensnared them in the first place.
Yet what is so powerful is that both the trap of vowing, and the release of התרת נדרים, comes from the פה – the mouth – which is our ultimate פתח, and this is because we can use our mouth for good or for bad; to trap or to solve; to hurt or to heal. So what we learn from here is that we should use that פתח constructively, because if we don’t, we can unfortunately fall into the trap of using it destructively.