On Nedarim 4b, the Gemara brings a statement of Shmuel:
האומר לחבירו מודר אני וכו’. אמר שמואל: בכולן עד שיאמר שאני אוכל לך, שאני טועם לך
As the Gemara intially understands it, Shmuel teaches that if a person only said the words, “you are vowed from me” this would not create any neder. Only by adding “..from what I may eat of yours” will a neder be created.
This seems strange. How could Shmuel suggest that the words “I am vowed from you” has zero connotation of a vow when the term “vow” was explicitly stated?
Artscroll note 16 answers thusly:
“Perhaps the reason is because ‘I am vowed from you’ is understood as an expression of displeasure, meaning ‘I will have nothing to do with you, as if I was under vow.’
Begging the forgiveness of the esteemed author of note 16, I can’t fathom what he is saying. For it seems to me that the words, “I am vowed from you” mean “I am vowed from you” and not some expression of displeasure.
I would suggest instead, that Shmuel is teaching us that even if you clearly express an intent to create a neder, that expression is meaningless unless it connects to something tangible, such as another person’s food. This comes from the Gemara’s statement above (2b) that Nedarim only go into effect on tangible objects. It therefore wouldn’t be unreasonable to say that a Neder is only properly expressed when this facet is incorporated into the vower’s words. Hence “I am vowed from you” is not good enough (what on that other person is being vowed from? His property? His food?).
That is perhaps the rationale of Shmuel’s teaching, as the Gemara understands it at this stage.