Babylonian Talmud Shabbat 157b
Ula visited the Exilarch’s house [on Shabbat]. He saw that Rabbah b. Rav Huna was sitting with a tub of water and measuring it. He said to him, “While we say that our Rabbis permitted measuring for the sake of a mitzvah, if it is not for the sake of a mitzvah did they permit it?!?” He replied, “I’m just playing around.”
עולא איקלע לבי ריש גלותא חזייה לרבה בר רב הונא דיתיב באוונא דמיא וקא משח ליה אמר ליה אימר דאמרי רבנן מדידה דמצוה דלאו מצוה מי אמור אמר ליה מתעסק בעלמא אנא
Our Sages forbade us to take measurements on Shabbat. In their day, as in ours, measurements were most often associated with commerce. They strove to create a day free from the workaday stresses of acquisition. We see this sensitivity in this prohibition, as in the many prohibitions and commandments we have seen throughout the year. As we began the year, I hoped to convey that Shabbat is first and foremost a spiritual discipline. The God of Israel demands that we rest each week, that we may dedicate the work of our hands throughout the week for the sake of Heaven. We attempt a perfect rest each week, knowing that our anxieties will likely break into our day of calm marring our rest, yet we try again the next week.
In our passage, we find Ula shocked to discover Rabbah b. Rav Huna engaging in an act that Ula perceives as violating the character of the day: Rabbah b. Rav Huna sits with a cup measuring the water that a particular tub will hold. Ula sees this as violating the Sages’ words. Rabbah b. Rav Huna will enter the world of commerce and anxiety by measuring the capacity of the tub. Rabbah b. Rav Huna deflates the situation in one sentence. He is just entertaining himself, not really measuring water or the tub for any real reason. This sort of entertainment is permitted.
I hope you have found my Torah entertaining and enlightening over the course of the year. It has been a privilege to learn with you all. Shabbat shalom and hag sameah!