Calvin (from the Institutes, Book III, chapter XVII.10):
A work begins to be acceptable only when it is undertaken with pardon. Now whence does this pardon arise, save that God contemplates us and our all in Christ? Therefore, as we ourselves, when we have been engrafted in Christ, are righteous in God’s sight because our iniquities are covered by Christ’s sinlessnes, so our works are righteous and are thus regarded because whatever fault is otherwise in them is buried in Christ’s purity, and is not charged to our account. Accordingly, we can deservedly say that by faith alone not only we ourselves but our works as well are justified. Now if this works righteousness — whatever its character — depends upon faith and free justification and is effected by this, it ought to be included under faith and be subordinated to it, so to speak, as effect to cause, so far is it from having any right to be raised up either to destroy or becloud justification by faith.”