Christ perfectly kept the law for all of His people.
"We must have a righteousness, not only in which you and I cannot find a flaw, but in which God cannot find a flaw. And if we ourselves see nothing but sin in our own, and find fault with the very best that we can do and say all our righteousnesses are but filthy rags, how heart-breaking must we feel to present such a one before infinite purity and perfection. We must have a righteousness in which Jehovah himself cannot find a flaw, a righteousness which Jehovah cannot mend, a righteousness which neither sin nor Satan can mar; and unless we have on a righteousness of this nature, we can never enter into the blessedness of the world to come.
Where, then, are we to find it? Eternal praises to the matchless mercy of a covenant God, we have it in the blessed Person, glorious work, and spotless obedience of the Lord Jesus Christ! And, therefore, as it was essential for him to fulfill all righteousness for his people, he loved the Lord his God with all his heart, with all his mind, and with all his strength. He began at the beginning, and went through holily, righteously, and steadily every step of the law of God; and all in justice and righteousness. He fulfilled every iota of it, and gave it immortal glory and honour. The law could only require the perfect obedience of a perfect man, but he gave it the perfect obedience of the God-man, and stamped for ever a holy dignity and majesty on it, in order to manifest that this glorious righteousness is suited to every sinner’s case, to all their needs, and to honour and glorify all the perfections of God; and thus he has “for ever perfected them that were sanctified,”—all those who were set apart for himself. They are perfected for ever in his own blessed obedience and spotless righteousness; and this righteousness which God gives shall endure for ever. As for you who have a righteousness of your own, you never can feel your need of Christ’s righteousness; and if any one should insult you by speaking of it, you are wrapped up so snugly in your own pretty works that it would be an insult to your dignity to have his. The same as it would be an insult to the queen for you to make a basket of bulrushes, and present it to her as something very valuable; she would not receive it at your hands. So it is with you, when we speak of this blessed righteousness. You do not know your need of it, and it is an insult to your pride to mention it. But for the poor creature who feels himself to be a loathsome, vile, and ruined sinner, and is brought experimentally to feel what he is before a heart-searching God, and that every iota of the law is against him—for God to give this righteousness to him, to put it upon him and communicate the power of it to his soul, why it will raise and exalt him to such a blessed enjoyment of God’s righteousness that his tongue will sing aloud and speak forth praise to the honour and glory of his blessed name; and he will say, “My soul shall be joyful in my God; I will glory in the God of my salvation; for he hath covered me with the robe of righteousness; he hath adorned me with the garments of salvation.” And thus his tongue shall speak of God’s righteousness and of his praise all the day long."
- excerpt from a sermon by William Gadsby, entitled, "The Tongue Speaking of Righteousness", preached at Zoar Chapel, Great Alie Street, London, on June 1, 1843