Why do we not say a beracha [blessing] when giving tzedakka [charity]?
Dear Barnet Shapiro,
Your question is dealt with by the early commentators. One answer given is as follows: One does not make a beracha on an action which is dependent on another person's acceptance, as there is a chance that the other person might not accept and hence the beracha would in vain.
- Teshuvot Rashba Vol. 1 ch. 18, 254 and Vol. 3 ch. 283 and affiliated to Ramban 189
- Ketuboth 40a