ARGUMENTS WITH ONE'S CHAVRUSA

It seems that Jack and I have more arguments than one would expect after learning together for 30 yrs. This time we argued about the obligation to give 10% of your income for tzedakah. He said that it was a mitzvah d'rabbanan. If you give 9.5% you have transgressed a rabinnic law which has severe consequences . I said NO. it is a midos tovos. It is a recommendation by the rabbis but not an obligation. I asked several rabbinic neighbors and was surprised to learn that none of them new what the nature of this 10% was. In shul , I finally asked Rabbi Eisenberger and he resolved the argument in the style of King Solomon. He said we were both correct. There are several different opinions from saying that it is a torah-like law- others that it was a rabbinic law and still others who maintained that it was a good mida recommendation. May all your arguments be resolved . Have a happy erev pesach. ( Erev peasach is that period of time between the last hamantasch and the first bite of hand shurah matzah)
the DAD