Tertullian

Plainly we do, if we are observers of Jewish ceremonies, of legal solemnities: for those the apostle unteaches, suppressing the continuance of the Old Testament which has been buried in Christ, and establishing that of the New. But if there is a new creation in Christ, our solemnities too will be bound to be new: else, if the apostle has erased all devotion absolutely "of seasons, and days, and months, and years," why do we celebrate the passover by an annual rotation in the first month? Why in the fifty ensuing days do we spend our time in all exultation? Why do we devote to Stations the fourth and sixth days of the week, and to fasts the "preparation-day? " Anyhow, you sometimes continue your Station even over the Sabbath,-a day never to be kept as a fast except at the passover season, according to a reason elsewhere given.