Laws and Customs that Merit a Good Parnassa (19)
Shabbos. The day of Shabbos, in general, is the day that brings down blessings for the following six days, as we declare in the words of Lecha Dodi: "לקראת שבת לכו ונלכה כי היא מקור הברכה" - Shabbos is the source of blessing. Apart from this generality, there are specific deeds that one can do before, during and after Shabbos, that can bring parnassa. At the same time, there are things to avoid that can be detrimental to one’s parnassa.
Preparing for Shabbos. The physical work of preparation that one does before Shabbos (1), and learning its halachos and other Shabbos topics (2), can help bring good parnassa.
Work on Friday Afternoon. The Gemara in Pesachim (3) tells us that one who does work on Friday afternoon, from the time of Mincha and on, will not see any parnassa-profit from that work. This means that even if one seems to profit from a specific venture that he transacted on Friday afternoon, some other loss or expenditure will come his way that will cancel out this profit. This prohibition was instituted to allow time to make proper preparations for Shabbos. Which type of work are we referring to? Work that includes extensive labor like plumbing, painting a house, repairing a car, etc.
The Following Cases Are not Included in the Prohibition.
Things needed for honoring Shabbos like cooking, haircuts, housecleaning, mending Shabbbos clothes, etc. are permitted to be done on Friday afternoon (4).
One who is employed by others, and is expected to work as much of the day as possible, is permitted to do so (5). Since they will be busy on Friday, these people should make their Shabbos preparations on Thursday, if necessary.
People who sell products are permitted, such as storekeepers and salesmen (6). However, they must make sure not to work too close to Shabbos.
When Does this Restriction Start? The above mentioned Gemara states that the restriction starts from the time of Mincha. Rabbeinu Meir holds from Mincha Gedolah - a half hour after halachic midday. Rashi holds that it starts from Mincha Ketana, and the Mishna Berura (7) rules that if one wants to be lenient like Rashi, he can do so.
When exactly is Mincha Ketana? According to the custom of considering one and a quarter seasonal hours before the sun sets as"פלג המנחה" for candle lighting, this restriction starts another one and a quarter hours before that, meaning two and one half seasonal hours before sunset. (This might sound contradictory to the words of the Mishna Berura 256:1. To explain why it is not, is too lengthy for this column. See Piskei Teshuvos, newer version 251:1 and note 5, M.B. Dirshu 251:3)
(1) בראשית רבה יא-ד, וע' שפת אמת פרשת ויחי תרלד (2) חת"ס בתורת משה בשלח (3) נ:ב (4) או"ח רנא:ב (5) משנה ברורה רנא:ג (6) שם רנא:א (7) רנא:ג