In works and alms, even if by smallness of power less be done, that the will itself is sufficient
In the second Epistle of Paul to the Corinthians: If there be a ready will, it is acceptable according to what a man has, not according to that which he has not; nor let there be to others a mitigation, but to you a burdening.
Source: The Treatises of Cyprian (New Advent)