Charity is correct and just. First of all, it is just (tzodek) that the receiver should get what he appropriately needs. But there is a second meaning [of tzedek] that appears in the Prophets: What is justly done for the soul of the giver. One who performs good deeds gives to his own soul the good that it deserves.

The word tzedaka (charity) is derived from tzedek (justice). It denotes the act of giving to each person what they are due, and showing kindness to each person as they deserve. In the books of the Prophets, however, the expression tzedaka is not used in the first sense, and does not apply to the payment of what you owe to others. When you give a hired worker his wages, or pay back a debt, this is not called tzedaka. But when you fulfill duties toward your fellow man out of moral virtue, such as healing the wounds of those who are injured, this is called tzedaka…. When you act according to moral virtues, you do justice to your rational soul, giving it what it is due. (Rambam, Guide of the Perplexed III:53)