For almost all churches throughout the world celebrate the sacred mysteries [Lord's supper] on the Sabbath of every week." Socrates Scholasticus, Eccl. History
"Then the spiritual seed of Abraham [Christians] fled to Pella, on the other side of Jordan, where they found a safe place of refuge, and could serve their Master and keep His Sabbath." Eusebius's Ecclesiastical History.
Philo, the philosopher and historian, affirms that this Sabbath was on the seventh-day of the week.
2ND CENTURY
"The primitive Christians had a great veneration for the Sabbath, and spent the day in devotion and sermons... They derived this practice from the Apostles themselves, as appears by several scriptures to that purpose." D. T H. Morer (Church of England) Dialogues on the Lord's Day, London, 1701.
2ND, 3RD, 4TH CENTURIES
"From the apostles' time until the Council of Laodicea [364 AD], the holy observation of the Jews' Sabbath continued, as may be proved out of many authors: yea, notwithstanding the decree of the council against it." John Ley, Sunday A Sabbath, London, 1640.
3RD CENTURY
"As early as 225 A.D. there existed large Sabbath-keeping bishoprics or conferences of the Church of the East stretching from Palestine to India." Mingana, Early Spread of Christianity.
4TH CENTURY
"In the church of Milan (Italy) it seems that the Saturday was held in a fair esteem. Not that the Eastern churches or any of the rest which observed that day, were inclined to Judaism; but that they came together on the Sabbath day to worship Jesus the Lord of the Sabbath." Dr. Peter Heylyn, History of the Sabbath, London, 1636.
"For more than 17 centuries the Abyssinian Church continued to sanctify Saturday as the holy day of the 4th commandment." Ambrose de Morbius.
"Ambrose, the celebrated bishop of Milan, said that when he was in Milan he observed Saturday, but when in Rome observed Sunday. This gave rise to the proverb, 'When you are in Rome, do as Rome does."' Heylyn, History of the Sabbath
Persia 335-375 A.D. "They [the Christians] despise our sun-god. Did not Zoroaster, the sainted founder of our divine beliefs, institute Sunday one thousand years ago in honor of the sun and supplant the Sabbath of the Old Testament? Yet these Christians have divine services on Saturday." O'Leary, The Syriac Church and Fathers.
5TH CENTURY
"Augustine [whose testimony is made the more impressive by his being a committed Sunday-keeper] shows.. that the [seventh-day] Sabbath was observed in his day 'in the greater part of the Christian world."' Nicene and Post-Nicene Fathers, 1st series, voL 1, pp. 353, 354
"Down even to the fifth century the observance of the Jewish Sabbath was continued in the Christian church." Lyman Coleman, Ancient Christianity Exemplified , p. 526.
"In 411 [Mingana, leader of the Eastern Churches] appointed a metropolitan director for China. These churches were sanctifying the seventh day." J. F. Colthart, The Sabbath Through The Centuries, p. 11.
6TH CENTURY
"In this latter instance they [the Scottish Church] seem to have foflowed a custom of which we find traces in the early monastic church of Ireland by which they held Saturday to be the Sabbath on which they rested from all their labors." W. T. Skene, Adamnan's Lfe of St. Columba, 1874, p. 96.
On Columba of lona: "Having continued his labors in Scotland thirty-four years, he clearly and openly foretold his death, and on Saturday, June ninth, said to his disciple Diermit: 'This is the day called the Sabbath, that is, the rest day, and such it will truly be to me; for it will put an end to my labors."' Butler's Lives of the Saints, article on "St. Columba."
7TH CENTURY
"It seems to have been customary in the Celtic churches of early times, in Ireland as well as Scotland, to keep Saturday ... as a day of rest from labor. They obeyed the fourth commandment literally on the seventh day of the week." Jas. C. Moffatt, The Chutch In Scotland.
From Gregory I, Pope of Rome 590-604: "Roman citizens: It has come to me that certain men of perverse spirit have disserninated among you things depraved and opposed to the holy faith, so that they forbid anything to be done on the day of the Sabbath. What shall I call them except preachers of anti-christ?"