Another way we show our eagerness to greet Shabbos is through tosefes Shabbos, adding some extra time to Shabbos just before its start and at its conclusion. According to most early commentators, this is a Torah obligation. During this time, all melacha is forbidden as though it is truly Shabbos (Shulchan Aruch 261: 2).
How does one fulfill the mitzvah of tosefes Shabbos? As mentioned earlier, at the conclusion of Lecha Dodi we welcome Shabbos saying, “Enter, O bride! Enter, O bride!” This greeting is an acceptance or welcoming of Shabbos and preferably should be said while it is still weekday (i.e. before sunset) (Mishna Berura 261: 31).
Since one is obligated to fulfill this mitzvah before sunset, if circumstances will prevent him from finishing Lecha Dodi by then, he should accept Shabbos Beforehand. According to most opinions, this can be done by making a formal declaration, saying, “I accept Shabbos upon myself” (Rema 608: 3; Mishna Berura 261: 21). Some poskim say that a person need only think quietly, “I accept Shabbos upon myself” (Bach and Gra 608: 3).
Text Copyright © 2014 by Rabbi Daniel Travis and Torah.org