Now he could not mean to contradict himself in saying, “The doers of the law shall be justified,” as if their justification came through their works, and not through grace; since he declares that a man is justified freely by His grace without the works of the law, intending by the term “freely” nothing else than that works do not precede justification. For in another passage he expressly says, “If by grace, then is it no more of works; otherwise grace is no longer grace.” But the statement that “the doers of the law shall be justified” must be so understood, as that we may know that they are not otherwise doers of the law, unless they be justified, so that justification does not subsequently accrue to them as doers of the law, but justification precedes them as doers of the law.

Augustine, De spiritu et littera, 26.45; “A Treatise on the Spirit and the Letter,” in Saint Augustin: Anti-Pelagian Writings, ed. Philip Schaff, trans. Peter Holmes, NPNF 5.102.