The first two and the last two days of Pesah are full Festival days, to be observed negatively by abstention from work, and positively by holiday rejoicing.

The prohibition of work (melakhah) on the Festivals, Pesah, Shavuot, Sukkot, Shemini Atzeret, and Simhat Torah (as well as Rosh Hashanah), is based on the prohibition of work on the Sabbath, the details of which are given in the Mishnah, Tractate Shabbat. In the Mishnah, at 7:2, thirty-nine basic categories of prohibited work (avot melakhah) are given. Traditionally, these types of activity are seen as those needed in the construction and operation of the Tabernacle. We might note that they are the kinds of activities involved in providing food, clothing, and shelter. Dependent on these avot melakhah are various tol’dot melakhah, activities which involve the same action as avot melakhah, but in a different context. The third type of activity prohibited on the Sabbath is one which rabbinical tradition has proscribed as resembling, leading to, or being associated with melakhah. The application of these principles to today's situation may be the subject of debate, but it should be understood that the 39 avot melakhah form an intrinsic part of the concept of Shabbat, and, hence, of the Festivals.

Some examples of common activity in which we should not engage on Shabbat are: gardening, grinding food, cooking, cutting hair, cloth, paper, or other materials, doing laundry, sewing, writing or erasing, building (i.e. changing the physical configuration of things to make some use of them), kindling or extinguishing a fire, adjusting any complex mechanism, and carrying articles outside.

All of the above applies to the Sabbath. On a Festival, the situation is somewhat different. Whereas, with regard to the Sabbath, we are told "You shall not do any work," (Exodus 20:l0), with regard to the Festivals the rule is "No work at all shall be done on them; only that every person is to eat, that alone may be prepared for you." (Exodus l2:l6). Thus, certain activities, prohibited on the Sabbath, are permitted on a Festival. It is permitted to carry things out of doors on a Festival (This permission is derived from the necessity of carrying food from the house to the sukkah on Sukkot). One may also cook and prepare food, and make other use of fire on a Festival. In order to safeguard the sanctity of the Festival, certain restrictions are placed on the preparation of food and the use of fire:

In Deuteronomy l6:l4 we read "you shall rejoice in your Festivals," and simhah, joy, is an intrinsic part of Festival observance. We wear our best clothes on Yom Tov, eat large meals, say the appropriate kiddush over wine, and chant the joyful Hallel psalms at the synagogue.