Is there any tradition of the Church for its first 500 years that in any way resembles modern sabbatarianism? Is it a hold over from later Popery?
Tertullian was rather clear that the Christian was under no obligation to uphold any sort of sabbath or circumcision:
Therefore, since God originated Adam uncircumcised, and inobservant of the Sabbath, consequently his offspring also, Abel, offering Him sacrifices, uncircumcised and inobservant of the Sabbath, was by Him commended; while He accepted what he was offering in simplicity of heart, and reprobated the sacrifice of his brother Cain, who was not rightly dividing what he was offering. Noah also, uncircumcised— yes, and inobservant of the Sabbath— God freed from thedeluge. For Enoch, too, most righteous man, uncircumcised and inobservant of the Sabbath, He translated from this world; who did not first taste death, in order that, being a candidate for eternal life, he might by this timeshow us that we also may, without the burden of the law of Moses, please God. Melchizedek also, the priest of the most high God, uncircumcised and inobservant of the Sabbath, was chosen to the priesthood of God. Lot, withal, the brother of Abraham, proves that it was for the merits of righteousness, without observance of the law, that he was freed from the conflagration of the Sodomites (Chapter 2, An Answer to the Jews).
Likewise, in Chapter 4, Tertullian argues that the Sabbath was fulfilled in Christ:
the observance of the Sabbath is demonstrated to have been temporary....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, andsabbath after sabbath; and all flesh shall come to adore in Jerusalem, says the Lord; 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 You. Thus, therefore, before this temporal sabbath, there was withal an eternal sabbath foreshown and foretold (Chapter 4).
The Synod of Laodicea clearly differentiated between the Sabbath and the Lord's Day, and even permitted work on the Lord's Day. This shows that the modern, legalistic view of the Lord's Day as the new Sabbath, with identical obligations, is clearly a later innovation:
Christians must not judaize by resting on the Sabbath, but must work on that day, rather honouring the Lord's Day; and, if they can, resting then as Christians. But if any shall be found to be judaizers, let them be anathema from Christ. (Canon 29)
Here Cyprian, when defending the practice of
not delaying baptism to the eighth day after birth so that it may directly follow the pattern of circumcision, clearly differentiates between the Lord's Day and the Sabbath. Further, he not view baptism as a replacement for circumcision as the Covenant Theology types argue, but rather in effect a shadow of the spiritual circumcision that is made possible by Christ being resurrected on the "eighth day."
For in respect of the observance of the eighth day in the Jewish circumcision of the flesh, a sacrament was given beforehand in shadow and in usage; but when Christ came, it was fulfilled in truth. For because the eighth day, that is, the first day after the Sabbath, was to be that on which the Lord should rise again, and should quicken us, and give us circumcision of the spirit, the eighth day, that is, the first day after the Sabbath, and the Lord's day, went before in the figure; which figure ceased when by and by the truth came, and spiritual circumcision was given to us (To Fidus, on the Baptism of Infants, Chapter 4).
Later Church Tradition, evidenced by the Apostolic Constitutions (380 AD?), started contriving days of necessary fasting and such. Interestingly enough, the idea that the Christian was duty-bound to do this on a Sunday did not enter anyone's minds. Rather, good Friday was the only Sabbath:
But there is one only Sabbath to be observed by you in the whole year, which is that of our Lord's burial, on which men ought to keep a fast, but not a festival (Apostolic Constitutions, Book VII, Chapter XXIII).
In fact, I cannot find anywhere a single
"mention that the Sabbath day rest was changed into Sunday day rest."