I also adduced another passage in which Isaiah exclaims: "Hear My words, and your soul shall live; and I will make an everlasting covenant with you, even the sure mercies of David. Behold, I have given Him for a witness to the people: nations which do not know you shall call on you. Peoples who do not know you shall escape to you, because of your God, the Holy One of Israel; for He has glorified you." This same law you have despised, and His new holy covenant you have slighted; and now you neither receive it, nor repent of your evil deeds. "For your ears are closed, your eyes are blinded, and the heart is hardened," Jeremiah has cried; yet not even then do you listen. The Lawgiver is present, yet you do not see Him; to the poor the Gospel is preached, the blind see, yet you do not understand. You have now need of a second circumcision, though you glory greatly in the flesh. The new law requires you to keep perpetual sabbath, and you, because you are idle for one day, suppose you are pious, not discerning why this has been commanded you: and if you eat unleavened bread, you say the will of God has been fulfilled. The Lord our God does not take pleasure in such observances: if there is any perjured person or a thief among you, let him cease to be so; if any adulterer, let him repent; then he has kept the sweet and true sabbaths of God. If any one has impure hands, let him wash and be pure.
For Isaiah did not send you to a bath, there to wash away murder and other sins, which not even all the water of the sea were sufficient to purge. But, as might have been expected, this was that saving bath of the olden time which followed those who repented, and who no longer were purified by the blood of goats and of sheep, or by the ashes of an heifer, or by the offerings of fine flour, but by faith through the blood of Christ, and through His death, who died for this very reason, as Isaiah himself said, when he spoke thus: "The Lord shall make bare His holy arm in the eyes of all the nations, and all the nations and the ends of the earth shall see the salvation of God. Depart, depart, depart, go out from there, and touch no unclean thing; go out of the midst of her, be clean you that bear the vessels of the Lord, for you go not with haste. For the Lord shall go before you; and the Lord, the God of Israel, shall gather you together."
For Isaiah did not send you to a bath, there to wash away murder and other sins, which not even all the water of the sea were sufficient to purge. But, as might have been expected, this was that saving bath of the olden time which followed those who repented, and who no longer were purified by the blood of goats and of sheep, or by the ashes of an heifer, or by the offerings of fine flour, but by faith through the blood of Christ, and through His death, who died for this very reason, as Isaiah himself said, when he spoke thus: "The Lord shall make bare His holy arm in the eyes of all the nations, and all the nations and the ends of the earth shall see the salvation of God. Depart, depart, depart, go out from there, and touch no unclean thing; go out of the midst of her, be clean you that bear the vessels of the Lord, for you go not with haste. For the Lord shall go before you; and the Lord, the God of Israel, shall gather you together."
Justin Martyr, Dialogue with Trypho, 12-13