We are beginning Klal 5, siman 1. The Chayei Adam writes that one should be careful to accept Shabbos early. One can accept Shabbos from plag hamincha, which is 1 1/4th hour before nighttime. The Chayei Adam is following the opinion that plag is calculated based on nightfall. It is the approach of the Shulchan Aruch as well, and is often referred to as the opinion of the Magen Avraham. It is based on the opinion that daytime is measured from dawn to nightfall, and not sunrise to sunset. This opinion considers part of bein hashmashos as daytime.
The definition of a halachic hour and a quarter will depend on the amount of daytime. If the day is longer, the hour and a quarter will be longer; if it is shorter, it will be shorter. Thus, it is possible for this halachic hour and a quarter to be either less or more than 75 minutes.
The Chayei Adam writes that one who accepts Shabbos from two hours before nightfall is praiseworthy and should be considered holy. However, if one accepts Shabbos more than two hours before nightfall, they have not accepted Shabbos as it is too early. The Mishnah Berurah has difficulty understanding the Chayei Adam’s maximum of two hours. To understand the Chayei Adam’s opinion, we will need to discuss more background, which we will do in the next shiur, be’ezras Hashem.
The Chayei Adam continues, and writes that, on the minimal end, one must cease all melacha from 30 minutes before nightfall, as one must add from chol to kodesh, meaning from the week to Shabbos. It is important to note that the Chayei Adam writes to cease from work 30 minutes before nightfall, as opposed to sunset.
The actual bein hashmashos period itself does not count towards the mitzvah of tosefes Shabbos. One must refrain from melacha then because of the halachic doubt of the status of bein hashmashos.
Therefore, if the bein hashmashos period is, for argument’s sake, 25 minutes, ceasing 30 minutes before nightfall will give the person five minutes of tosefes Shabbos before sunset. This amount allows for the minimal amount of tosefes Shabbos, which, as we have learned previously (shiur S0040), is approximately 2-4 minutes. Thus, the Chayei Adam is explaining that one must minimally accept Shabbos with enough time for tosefes Shabbos.
Summary
- One should accept Shabbos as early as they can.
- The Chayei Adam holds that one can accept Shabbos from plag hamincha (which he calculates to nightfall) or even up to two hours before nightfall.
- Minimally, the Chayei Adam holds one should accept Shabbos 30 minutes before nightfall.
- Bein hashmashos does not count towards the mitzvah of tosefes Shabbos.
