BG 17.19-21
That austerity done under a deluded understanding, with self-torture, or with the object of destroying another, that is declared of darkness. That alms given to one who does nothing in return, believing that a gift ought to be made in a fit place and time to a worthy person, that alms is accounted pure. That given with a view to receiving in return, or looking for fruit again, or grudgingly, that alms is accounted of passion.