Musar על אבות 3:15

Our Sages, of blessed memory, said further, "The quality of generosity depends upon habit, for a man cannot be called generous unless he gives of his own free will at all times, and at all hours, according to his ability. A man who gives a thousand gold pieces to a worthy person at one time is not as generous as one who gives a thousand gold pieces on a thousand different occasions, each to a worthy cause. For the man who gave the thousand gold pieces at one time had a sudden impulse to be generous, but after that the desire left him. Also in the matter of reward, one cannot compare a man who redeems one captive for a hundred dinars, or gives alms to one poor man in the amount of one hundred dinars (which is completely sufficient for the poor man's needs) with a man who has redeemed ten captives, or has helped to cover the needs of ten poor men, each one receiving ten dinars. Concerning this our Sages said, "Everything must be according to the multitude of the task" (Aboth 3:15); they did not say according to the greatness of the task."