Archibald Alexander: The righteousness of Christ alone is the ground of justification

Archibald Alexander explains that Christ's perfect obedience in keeping the law and satisfying the penalty encompasses the righteousness by which we are justified:

By the righteousness of Christ, we mean, all that he did and suffered to satisfy the broken law of God, for those whose salvation he undertook to secure. … as has been correctly observed by Dr. Owen and others, 'in suffering he obeyed, and in obeying he suffered.' It is sufficient, that we find in him, a full satisfaction both to the penal and preceptive requisitions of the law. (Archibald Alexander, A Treatise on Justification by Faith Alone)