Mishnah: A person must say three things in his house as it becomes dark on Shabbat eve, "Did you tithe? Did you prepare the eruv?" Light the [Shabbat] lamp!
Talmud: Rabba bar Rav Huna said, "Even though our Rabbis say, 'a person must say three things,' one should say them calmly so that the other [members of the family] will accept them from [the head of the household]."
Certain things must be done before Shabbat begins. Our mishnah gives a checklist of three things about which the head of a family must inquire as Shabbat begins. Have the necessary tithes been taken from the produce? Has the boundary delineating the extent of private space, the eruv, been properly established? Have the Shabbat lights been lit? Here the concerns are, in order: 1. food; 2. housing; and 3. peace and comfort. In the land of Israel, if the proper tithes have not been taken from the produce, one may not eat of it. One may not remove the tithes on Shabbat. One may only carry within a "private domain" on Shabbat, so the eruv is crucial to determining where one may make use of one's possessions on Shabbat. Finally, the Shabbat lights are the only source of artificial illumination on Shabbat, providing both comfort and peace in the home.
One can imagine the level of stress the head of the household must have felt in this period as the light of the day began to fade. Was everything ready? The temptation to give in to stress and anger must have been great. Rabba bar Rav Huna reminds us that as we prepare for Shabbat, we must remember to preserve an air of calm and respect for one another. Shabbat is a time of wholeness and peace. We must remember this even as we go about our preparations for our day of rest.