Chapter 29
Laws Derived from Isaiah: Running, Walking, Commerce, Measuring, Reading, Speaking
SPEAKING ABOUT THINGS ONE IS FORBIDDEN TO DO ON SHABBATH AND YOM TOV
62. One may talk about the price of an article one has bought (except in the circumstances mentioned in paragraph 63 below),
a. when one has already paid for it or
b. even when one has not yet paid for it, if the price is fixed and does not require calculation.
63.a. One should not tell another person that one has bought a particular item in a certain shop, or that one has paid a particular amount for it, if one in fact intends the information to be of practical benefit.
63.b. This could be the case when the person to whom one is speaking is himself thinking of purchasing an article of that kind.

