Sefer Ha’mitzvos Ha’Katzar (the concise book of mitzvos)
By the Chofetz Chaim
This book lists the Torah mitzvos that can be observed today
First Section – the Positive Commandments
19. It is a positive commandment to sanctify the Shabbos day with words
CONTINUED FROM Mitzvah 19a
It is also a commandment to set the table Motzi Shabbos (Saturday night), even though one is only required to eat a kazi'as (the amount equal to the size of an olive), in order to escort the Shabbos queen.
The Ramban (R' Moses ben Nachman, Nachmonides) writes that also part of the positive commandment to remember the Shabbos day is to remember Shabbos every day of the week. Therefore when mentioning the days of the week, a person says "Echad B'Shabbos (the first day of Shabbos - this is Sunday), Sheni B'Shabbos (the second day of Shabbos - this is Monday), and so on. Also, in other matters, when he comes upon something good, he should designate it for Shabbos and say with his mouth "This is for Shabbos."
This mitzvah applies in all places and at all times, for men and for women.