"You shall surely open your hand "—Deuteronomy 15:8.
We are commanded to give charity to the indigent, to relieve them of their distress. We are commanded to feed the needy and provide them with whatever they lack.
Even a pauper who is sustained by charity is obligated to fulfill this mitzvah—by giving charity (even if only a pittance) to someone needier than himself, or someone in a similar predicament.
