For the source text click/tap here: Nedarim 13
To download, click/tap here: PDF
Our daf quotes a baraita that compares a neder and a shevua. According to the baraita, each of them has a strength that the other does not possess. Specifically, nedarim can be made on mitzvot, as well as on things that are permissible, while shevuot are limited and can be made only on permissible things. On the other hand, shevuot can take effect even on things that have no physical characteristics (davar she-en bo mamash) while nedarim can only take effect on things that have physical characteristics (davar she-yesh bo mamash).
It was said in the name of Rebbi how we know that there is a mitzvah to verbally sanctify a bechor that was born in his home etc.
The Gemara makes it clear that even though a firstborn animal (בכור) is sanctified automatically, nonetheless, it is appropriate to formally declare its sanctity.
Sefer Likutei Haze’evi extrapolates from this that when giving tzedaka it is appropriate to declare, “I am giving this money for tzedaka.” Although the money is tzedaka without a declaration, nevertheless there is a mitzvah to make this declaration.
Rav Moshe Alshich writes at length against those who publicly give tzedaka for their personal honor or the like.
We explore the tzedakah pledge and the status of charity in early rabbinic literature.