Sabbath to be specific. Not surprisingly many of them no longer teach the same way, and many of them have said protestantism is dead.
http://www.sundaylaw.net/opening/said.htmExcerpts
The Baptist ChurchThe Methodist Church"It is true that there is no positive command for infant baptism. Nor is there any for keeping holy the first day of the week. Many believe that Christ changed the Sabbath. But, from his own words, we see that He came for no such purpose. Those who believe that Jesus changed the Sabbath base it only on a supposition." Amos Binney, "Theological Compendium," pp. 180-181.
"No Christian whatsoever is free from the obedience of the commandments which are called moral." "The Sabbath was made for MAN; not for the Hebrews, but for all men." Methodist Church Discipline (1904), p.23
The Moody Bible Institute"The Sabbath was binding in Eden, and it has been in force ever since. This fourth commandment begins with the word 'remember,' showing that the Sabbath already existed when God wrote the law on the tables of stone at Sinai. How can men claim that this one commandment has been done away with when they will admit that the other nine are still binding?"....."I honestly believe that this commandment [the fourth, or Sabbath commandment] is just as binding today as it ever was. I have talked with men who have said that it has been abrogated (canceled), but they have never been able to point to any place in the Bible where God repealed it. When Christ was on earth, He did nothing to set it aside; He freed it from the traces under which the Scribes and Pharisees had put it, and gave it its true place. `The Sabbath was made for man, and not man for the Sabbath.' It is just as practicable and as necessary for men today as it ever was - in fact, more than ever, because we live in such an intense age." D.L. Moody, Weighed and Wanting, pg. 47.
The Congregational Church"It is quite clear that however rigidly or devotedly we may spend Sunday, we are not keeping the Sabbath.. The Sabbath was founded on a specific, divine command. We can plead no such command for the observance of Sunday.. There is not a single line in the New Testament to suggest that we incur any penalty by violating the supposed sanctity of Sunday." Dr R.W. Dale, "The Ten Commandments," pg. 106-107.
" The current notion that Christ and His apostles authoritatively substituted the first day for the seventh, is absolutely without any authority in the New Testament." Dr Lyman Abbot, in the "Christian Union," June 26, 1890.
The Lutheran Church"The observance of the Lord's day [Sunday] is founded not on any command of God, but on the authority of the church." Augsburg Confession of Faith, quoted in the Catholic Sabbath Manual, Part 2, Chap. 1, Sec.10.
"They [the Catholics] allege the Sabbath changed into Sunday, the Lord's Day, contrary to the Decalogue, as it appears, neither is there any example more boasted of than the changing of the Sabbath day. Great, say they, is the power and the authority of the church, since it dispensed with one of the Ten Commandments."
Martin Luther, Augsburg Confession of Faith, Art. 28, Par.9.
The Episcopal ChurchThe Presbyterian Church"There is no word, no hint in the New Testament about abstaining from work on Sunday. The observance of Ash Wednesday, or Lent, stands exactly on the same footing as the observance of Sunday. Into the rest of Sunday no Divine Law enters." Canon Eyton, in "The Ten Commandments"
"We must not imagine that the coming of Christ has freed us from the authority of the law; for it is the eternal rule of a devout and holy life, and must therefore be as unchangeable as the justice of God, which it embraced, is constant and uniform." John Calvin, Commentary on a Harmony of the Gospels, Vol. 1, pg. 277.
"The Sabbath is a part of the Decalogue - the Ten Commandments. This alone forever settles the question as to the perpetuity of the institution... Until, therefore, it can be shown that the whole moral law has been repealed, the Sabbath will stand... The teaching of Christ confirms the perpetuity of the Sabbath." T.C. Blake, D.D., Theology Condensed, pp.474,475
The Church Of England"Not any ecclesiastical writer of the first three centuries attributed the origin of Sunday observance either to Christ or to His apostles." Sir WILLIAM DOMVILLE, Examination of the Six Texts," pages 6, 7. (Supplement).
"There is no word, no hint, in the New Testament about abstaining from work on Sunday. . . into the rest of Sunday no divine law enters. . . The observance of Ash Wednesday or Lent stands exactly on the same footing as the observance of Sunday." CANON EYTON, "The Ten Commandments," pages 52, 63, 65
"Is there any command in the New Testament to change the day of weekly rest from Saturday to Sunday? None." Manual of Christian Doctrine," page 127
Eusebius, fourth-century bishop and friend of the wicked Emperor Constantine, whose Sunday law is the first on record, flatly says: "All things, whatsoever that it was duty to do on the Sabbath, these we have transferred to the Lord's day [as they had begun to call Sunday]." --"Commentary on the Psalms."
"The notion of a formal substitution by apostolic authority of the Lord's day [meaning Sunday] for the Jewish Sabbath [or the first for the seventh day]... and the transference to it, perhaps in a spiritualized form, of the sabbatical obligation established by the promulgation of the fourth commandment, has no basis whatever, either in Holy Scripture or in Christian antiquity." SIR WILLIAM SMITH AND SAMUEL CHEETHAM, A Dictionary of Christian Antiquities," Vol. II, page I82, Article "Sabbath."