No Biblical verse commands it, it hardly rates a mention in the Talmud, it is unknown to Maimonides, and nobody is quite certain as to why it is in the calendar at all.
In addition, it is the only occasion in the Jewish year which, with official sanction, is honoured in the breach rather than the observance, and transformed from a fast into something of a feast.
The most one finds in Talmudical literature is that there were pious individuals, most notably Rabbi Yehudah HaNasi, who chose to fast on Erev Pesach, but for different reasons.
In the Babylonian Talmud (Pesachim 108a) we learn that Rav Sheshet used to fast on the eve of Pesach. The Talmud considers but rejects the suggestion that this was because in Temple times a person could have been so busy eating on Erev Pesach that his paschal offering might have been neglected.
Instead it explains that Rav Sheshet was delicate, and if he ate during the day he would have no appetite left for the seder in the evening.
The Jerusalem Talmud (Pesachim 10:1) states that on Erev Pesach, Rabbi Yehudah Hanasi ate neither chametz nor matzah. It first explains that this was because he was a first-born (though it does not spell out the connection between being a first-born and observing a fast).
When the objection is raised that other sages were also first-born but did eat on that day, it concludes that because he was delicate, he fasted in order to preserve his appetite for the evening.
There was already a clear law (Mishnah Pesachim 10:1) that on Erev Pesach one should not eat from about mid-afternoon until nightfall, and hence the two rabbis we have mentioned, and others, may have voluntarily extended the period of fasting to cover the whole day.
Private fasts on Erev Pesach must have taken root to a sufficient extent to require clarification of their status and even permissibility in the mid-8th century post-Talmudical tractate, Sof’rim (21:2-3).
Stating that fasting is prohibited during Nisan because of happy events that occurred during the month, Sof’rim records that the prohibition is lifted on the eve of Pesach for two groups: (a) the first-born, and (b) the very pious (tz’nu’in) who preserve their appetite for the eating of matzah in the evening.
Thus an increasing number of individuals must have taken note of and followed the precedents mentioned in the Talmud and established a custom which did not yet have the force of law.
The Spanish authorities do not refer to the custom but it is known to, and finally accorded legal status by, the medieval Franco-German halachists as a fast for the first-born.
Tosafot (early 12th century) comments on the Talmudical story of Rav Sheshet by referring to fasting to preserve one’s appetite, and adds that the first-born are accustomed to fast on Erev Pesach as stated in tractate Sof’rim.
The Tur (early 14th century) makes the fast of the first-born obligatory, and links it with the miracle of the first-born Israelites in Egypt.
The fast must have become customary amongst Sephardim, despite the fact that Maimonides does not mention it, as Karo’s Shulchan Aruch stresses the obligation to observe it. Much care is devoted now to defining what is meant by a first-born and what to do if, for instance, Erev Pesach coincides with Shabbat.
Nonetheless the custom grew up of over-riding that fast by means of a se’udat mitzvah, a celebratory meal to mark a b’rit milah, pidyon ha-ben or siyyum (completion of the study of a tractate).
This new usage may have been prompted by psychological factors (the fast seems incongruous in an atmosphere of growing festival joy); practical reasons (fasting might affect one’s ability to prepare and enjoy the seder meal); and historical considerations (the fast is neither Biblical nor required by Talmudical law but developed over the ages as a custom).
The psychological factor comes into sharp focus in the thinking of the early Chassidic movement. In contrast to the more solemn and serious philosophy of life of the German pietists and the Lurianic Kabbalists, the Chassidim stressed gladness and enjoyment of life.
Thus Rabbi Tzvi Hirsch of Zhidachow (early 19th century) completely overturned the sentence we have quoted from the tractate Sof’rim by emending it to read, not habechorot mit’anin b’erev pesach (“the first-born fast on Erev Pesach”), but habechorot mit’an’gin b’erev pesach (“the first-born enjoy themselves on Erev Pesach“) (HJ Zimmels, Ashkenazim and Sephardim, 1958, p.245).
With the crosscurrents that first established and then more or less suspended the fast of the first-born, it would be interesting to discover whether any individuals or communities still maintain the practice of fasting and decline to take advantage of the more enjoyable alternative.
Visit Rabbi Apple’s Pesach page for many more of his insights into the festival.