Which day of the week is the biblical Sabbath? Many are confused over the issue, but such confusion is unnecessary. Not only is the answer plain from history and the Bible, it is also clear from the names for the seventh day of the week, Saturday, in many languages.
For example, the Spanish word for the seventh day of the week, Saturday, is sabado—the same word for "Sabbath." In fact, in more than 100 ancient and modern languages the seventh day of the week was named "Sabbath" or its equivalent. Following is a list of names for the seventh day of the week, Saturday, in 24 languages in which the root word Sabbath is still easily recognizable.
Such widespread use of forms of the word Sabbath for the seventh day of the week, Saturday, is clear evidence that speakers of these languages understood which day is the Sabbath.
Likewise, the fact that in no language do we see "Sabbath" similarly linked with Sunday, the first day of the week, is an obvious confirmation that this day never was considered the biblical Sabbath until later religious leaders tried to substitute Sunday for the true Sabbath day.