Only one of them could receive the birthright, and only one of them could be blessed as first born. Later in life though, they reconciled. The rabbis say that generosity stems from having an expansive eye, a good eye an eye that sees all the good that one has, and the good in other people. One can be generous with one's money, with one's self, and with one's wisdom. Tzedakah is a part of this, but also physically caring for others, hospitality and personal service.
Generous people feel a sense of solidarity with others, empathy and caring.
The Hebrew word nedivut comes from the Hebrew root Nadav, a word that is also the root of Nadiv, noble. Nobility is somehow tied to having a generous spirit. It is also part of the mitzvah of imitating God, whose love for us is an act of generosity. We are meant to be generous in our business dealings as well. Finally, the rabbis remind us that it is not just what we give but how we give it.