Friday sunset to Saturday sunset. Established at creation. Before sin. Before Israel. Before Sinai.
"It shall be unto you a sabbath of rest, and ye shall afflict your souls: in the ninth day of the month at even, from even unto even, shall ye celebrate your sabbath." Leviticus 23:32
"And the evening and the morning were the first day." Genesis 1:5
The biblical day begins at evening (sunset), not at midnight. This is established in the very first chapter of Scripture. The Sabbath runs from Friday sunset to Saturday sunset. The Roman midnight-to-midnight system is not biblical.
Yahuah did three things to the seventh day that He did to no other day in all of creation:
No man, no council, no pope, no emperor has the authority to transfer these three acts to another day. What Yahuah blessed, man cannot un-bless. What He set apart, man cannot make common.
The Sabbath existed before sin, during the Mosaic covenant, during Yahusha's ministry, after the execution stake, in the end times, and for all eternity. At what point was it supposedly abolished? There is no such point. It spans the entire timeline of Scripture from beginning to end.
In the ancient world, every royal seal contained three elements: the ruler's name, their title, and their territory. The Sabbath commandment is the only commandment that contains all three:
"For in six days Yahuah made heaven and earth..." (Exodus 20:11)
This is why the Sabbath is the seal of Yahuah. It bears His name, His title as Creator, and His dominion over all heaven and earth. No other commandment contains all three elements. The Sabbath is the authenticating mark of the Most High -- the sign that you belong to Him.
There is not a single verse in all of Scripture that commands worship on Sunday, transfers the Sabbath to Sunday, or even suggests that the first day of the week replaced the seventh. The change was made by men, not by Yahuah.
March 7, 321 AD -- Emperor Constantine issued the first civil Sunday law: "On the venerable Day of the Sun let the magistrates and people residing in cities rest." This was a pagan decree from a sun-worshipper, not a biblical commandment from the Most High.
Council of Laodicea (~364 AD) -- Canon 29: "Christians shall not Judaize and be idle on Saturday but shall work on that day; but the day of the Sun they shall especially honour." The institutional church explicitly forbade Sabbath-keeping and enforced Sunday.
This is not hidden history. It is openly documented. The change from Sabbath to Sunday was a human decree, enforced by Roman political and religious power.
"And he shall speak great words against the most High, and shall wear out the saints of the most High, and think to change times and laws." Daniel 7:25
Daniel prophesied that a power would arise that would "think to change times and laws." The Sabbath is both a time (the seventh day) and a law (the 4th Commandment). The Roman system changed the time of worship from Sabbath to Sunday and claimed authority over the law of the Most High. This is the fulfillment of Daniel's prophecy.
"The Church changed the observance of the Sabbath to Sunday by right of the divine, infallible authority given to her by her Founder, Jesus Christ. The Protestant, claiming the Bible to be the only guide of faith, has no warrant for observing Sunday." The Catholic Mirror, September 23, 1893
"Sunday is our mark of authority... The Church is above the Bible, and this transference of Sabbath observance is proof of that fact." The Catholic Record, September 1, 1923
The Roman church openly claims credit for the change and openly states that Sunday-keeping has no biblical basis. Those who keep Sunday on the authority of Scripture are following a tradition that Scripture never authorized. They are following Rome.