Leviticus 23:44

Feasts. In the institution of these feasts, as in the other regulations of Moses, there was something ceremonial, which might be altered, and something moral, which regards even those times when the Jewish religion was to cease. (St. Augustine, q. 43.)

Hence we must conclude, that the obligation of keeping certain days holy, must always remain. But those appointed for the Jews, as they foretold the future Messias, must be changed, lest otherwise we might seem to confess that he is still to come. (Romans xiv.; Galatians iv.; Colossians ii.) We are not therefore allowed to Judaize abstaining from work on the Jewish sabbath, (Council of Laodicea,) as Antichrist will require. (St. Gregory, ep. xi. 3.)

But we must keep Sunday instead, (as even Protestants maintain, though there be no Scripture for it) by authority of tradition, in memory of Christ's resurrection, &c. (St. Jerome, ep. ad Hed. ib.[ibid.?, St. Gregory, ep. xi. 3.?]; St. Augustine, de C.[City of God?] xxii. 30.) So also we observe the Christian festivals, in honour of our Lord and his saints, instead of those which God appointed for the Jews, either by himself or by his ministers: for we find that some were instituted after the time of Moses, (Esther ix., and 1 Machabees iv.) and these were sanctioned by the observance of Christ himself, It was the feast of the dedication, and Jesus walked in the temple, &c., John x. 22-23. (Worthington)