Ignatius apparently is the first to comment on the Sabbath question:
Let us therefore no longer keep the Sabbath after the Jewish manner, and rejoice in days of idleness; for “he that does not work, let him not eat.” For say the [holy] oracles, “In the sweat of thy face shalt thou eat thy bread.” But everyone of you keep the Sabbath after a spiritual manner, rejoicing in meditation on the law, not in relaxation of the body, admiring the workmanship of God, and not eating things prepared the day before, nor using lukewarm drinks, and walking within a prescribed space, nor finding delight in dancing and plaudits which have no sense in them. And after the observance of the Sabbath, let every friend of Christ keep the Lord’s Day as a festival, the resurrection-day, the queen and chief of all the days. Looking forward to this, the prophet declared, “to the end, for the eighth day,” on which our life both sprang up again, and the victory over death was obtained in Christ.
It seems he urged Christians to celebrate the sabbath – on Saturday, but to add to this a celebration on Sunday of Jesus’ Resurrection – “the queen and chief of all the days.” I’m not sure exactly what he means by these two phrases: “rejoicing in meditation on the law, not in relaxation of the body.” Is he saying, like some reformers, that taking the day off is not what the sabbath is for, but instead we should be doing bible studies and praying all day? Or is he simply saying we can chill out about the Hasidic-style meticulous rules while still honoring the intended restfulness of the day?