The Clearest Source for Marcion's Antitheses is ... Justin

[Stephan Huller]

Tertullian Against Marcion 2.21 (= Theophilus of Antioch's lost Against Marcion):

So also in the rest of his acts you accuse him of inconsequence and inconsistency (mobili et instabili), alleging that his instructions are in contradiction with one another (et in ceteris contrarietates praeceptorum): he forbids labour on sabbath days, and yet at the storming of the city of Jericho he commands the ark to be carried round during eight days which include the sabbath. This is because you neglect to look closely at the law concerning the sabbath, which forbids not divine but human labours. For it says, Six days shall thou labour, and do all thy works, but on the seventh day are sabbaths to the Lord thy God: on it thou shall not do any work. What work? Evidently, 'of your own'. It follows then that he was withdrawing from the sabbath those works which he had just appointed for the six days, 'thy works', meaning human daily tasks. But to carry the ark round cannot be considered a daily task, or a human one, but an infrequent one, a holy one, and, in view of God's actual command, a divine one. I might myself have enlarged upon the significance of this, but that it would take too long to explain the figurative meanings of every one of the Creator's activities—meanings to which perhaps you demur.

Tertullian Against the Jews 4 (= Justin's lost work but also Tertullian Adv Marc 3):

It follows, accordingly, that, in so far as the abolition of carnal circumcision and of the old law is demonstrated as having been consummated at its specific times, so also the observance of the Sabbath is demonstrated to have been temporary. For the Jews say, that from the beginning God sanctified the seventh day, by resting on it from all His works which He made; and that thence it was, likewise, that Moses said to the People: "Remember the day of the sabbaths, to sanctify it: every servile work ye shall not do therein, except what pertaineth unto life."62 Whence we understand that we still more ought to observe a sabbath from all "servile work" always, and not only every seventh day, but through all time. And through this arises the question for us, what sabbath God willed us to keep? ... But the Jews are sure to say, that ever since this precept was given through Moses, the observance has been binding (ex quo hoc praeceptum datum est per Moysen, exinde observandum fuisse). Manifest accordingly it is, that the precept was not eternal nor spiritual, but temporary, which would one day cease (sed temporale fuisse praeceptum quod quandoque cessaret). In short, so true is it that it is not in the exemption from work of the sabbath--that is, of the seventh day--that the celebration of this solemnity is to consist, that Joshua the son of Nun, at the time that he was reducing the city Jericho by war. stated that he had received from God a precept to order the People that priests should carry the ark of the testament of God seven days, making the circuit of the city; and thus, when the seventh day's circuit had been performed, the walls of the city would spontaneously fall. Which was so done; and when the space of the seventh day was finished, just as was predicted, down fell the walls of the city. Whence it is manifestly shown, that in the number of the seven days there intervened a sabbath-day. For seven days, whencesoever they may have commenced, must necessarily include within them a sabbath-day; on which day not only must the priests have worked, but the city must have been made a prey by the edge of the sword by all the people of Israel.

[Stephan Huller]

Tertullian Against Marcion 3.21:

Refuted however on the vocation of the gentiles, you now turn back to proselytes. You ask who they are from among the gentiles, that are passing over to the Creator, when those specifically mentioned by the prophet are proselytes, of a different condition, separate, by themselves: Behold, Isaiah says, proselytes by me shall come near unto thee,a showing that even proselytes were to come to God through Christ.

Tertullian Adv Iud 4:

Whence we discern that the temporal sabbath is human, and the eternal sabbath is accounted divine; concerning which He predicts through Isaiah: "And there shall be," He says, "month after month, and day after day, and sabbath after sabbath; and all flesh shall come to adore in Jerusalem, saith the Lord; "66 which we understand to have been fulfilled in the times of Christ, when "all flesh"--that is, every nation--"came to adore in Jerusalem" God the Father, through Jesus Christ His Son, as was predicted through the prophet: "Behold, proselytes through me shall go unto Thee." Thus, therefore, before this temporal sabbath, there was withal an eternal sabbath foreshown and foretold; just as before the carnal circumcision there was withal a spiritual circumcision foreshown. [6] In short, let them teach us, as we have already premised, that Adam observed the sabbath; or that Abel, when offering to God a holy victim, pleased Him by a religious reverence for the sabbath; or that Enoch, when translated, had been a keeper of the sabbath; or that Noah the ark-builder observed, on account of the deluge, an immense sabbath; or that Abraham, in observance of the sabbath, offered Isaac his son; or that Melchizedek in his priesthood received the law of the sabbath. Also the gentiles, which we are, likewise had their own mention, as people that were hoping in Christ: And in his name, he says, shall the gentiles hope.b Proselytes however, whom you interpolate into the prophecy concerning the gentiles, do not as a rule hope in Christ's name, but in Moses' law, from which their instruction comes: whereas the promotion of the gentiles has come about in these last days. In those very words Isaiah says, And it shall come to pass in the last days that the mountain of the Lord shall be manifest, namely, the majesty of God, and the temple of God above the top of the mountains, meaning Christ, the catholic temple of God, in whom God is worshipped, established above all the eminences of virtues and powers: and all the nations shall come to it, and many shall go and say, Come ye, let us go up into the mountain of the Lord, and into the house of the God of Jacob, and he will announce to us his way, and we will walk in it: for out of Sion shall go forth a law, and the word of the Lord out of Jerusalem. This way must be the gospel of the new law, and of the new word in Christ, no longer in Moses.