Pope Eugene IV, Council of Florence, Cantate Domino, 1441: “The Holy Roman Church firmly believes, professes and teaches that the matter pertaining to the law of the Old Testament, of the Mosaic Law, which are divided into ceremonies, sacred rites, sacrifices, and sacraments, because they were established to signify something in the future, although they were suited to divine worship at that time, after our Lord’s coming had been signified by them, ceased, and the sacraments of the New Testament began; and that whoever, even after the passion, placed hope in these matters of the law and submitted himself to them as necessary for salvation, as if faith in Christ could not save without them, sinned mortally. Yet it does not deny that after the passion of Christ up to the promulgation of the Gospel they could have been observed until they were believed to be in no way necessary for salvation; but after the promulgation of the Gospel it asserts that they cannot be observed without the loss of eternal salvation. All, therefore, who after that time (the promulgation of the Gospel) observe circumcision and the Sabbath and the other requirements of the law, it declares alien to the Christian faith and not in the least fit to participate in eternal salvation, unless someday they recover from these errors.”
Pope Benedict XIV in Ex Quo:
"The first consideration is that the ceremonies of the Mosaic Law *were abrogated* by the coming of Christ and that they can no longer be observed without sin after the promulgation of the Gospel. "
Pope Pius XII in Mystici Corporis:
"29. And first of all, by the death of our Redeemer, the New Testament took the place of the Old Law which had been abolished; then the Law of Christ together with its mysteries, enactments, institutions, and sacred rites was ratified for the whole world in the blood of Jesus Christ. For, while our Divine Savior was preaching in a restricted area - He was not sent but to the sheep that were lost of the House of Israel [30] - the Law and the Gospel were together in force; [31] but on the gibbet of His death Jesus made void the Law with its decrees [32] fastened the handwriting of the Old Testament to the Cross, [33] establishing the New Testament in His blood shed for the whole human race.[34] "To such an extent, then," says St. Leo the Great, speaking of the Cross of our Lord, "*was there effected a transfer from the Law to the Gospel, from the Synagogue to the Church, from the many sacrifices to one Victim, that, as Our Lord expired, that mystical veil which shut off the innermost part of the temple and its sacred secret was rent violently from top to bottom.*" [35]
30. *On the Cross then the Old Law died, soon to be buried and to be a bearer of death*, [36] in order to give way to the New Testament of which Christ had chosen the Apostles as qualified ministers; [37] and although He had been constituted the Head of the whole human family in the womb of the Blessed Virgin, it is by the power of the Cross that our Savior exercises fully the office itself of Head of His Church. "