Chapter 29
Laws Derived from Isaiah: Running, Walking, Commerce, Measuring, Reading, Speaking
MEASURING AND WEIGHING ON SHABBATH AND YOM TOV
38.a. It is permitted to measure and weigh for the purposes meng of a mitzva.*
38.b. Consequently,
1) one may measure a drinking cup to make sure it contains a sufficient quantity for making kiddush,
2) one may, on the first (or second) evening of Passover, measure or weigh the amount one has to eat to fulfill the mitzva of eating matza, and
3) one may measure the distance of two thousand amoth beyond the last house of the town, to ascertain how far one is allowed to walk on Shabbath.
39.a. It is permitted to measure and weigh for the purposes of a person who is ill.
39.b. Consequently,
1) one may measure and weigh the quantity of food needed for a sick person who has to eat on Yom Kippur (but see Chapter 39, paragraph 19),
2) one may take a sick person’s temperature (and see further Chapter 40, paragraph 2), and
3) one may make use of a stopwatch** or a sandglass for the purposes of a sick person, as where one has to feed him at fixed intervals or measure his pulse.
(See also Chapter 28, paragraph 30.)
________
*See however, paragraph 42 below regarding the separation of challa
**A duly qualified halachic authority should be consulted if one wishes to use an electronic watch.
