The prohibition on melacha is most severe during the first three days. The gemara says:

תלמוד בבלי מסכת מועד קטן דף כא עמוד ב
תנו רבנן אבל שלשה ימים הראשונים אסור במלאכה,
ואפילו עני המתפרנס מן הצדקה.
מכאן ואילך עושה בצינעא בתוך ביתו, האשה טווה בפלך בתוך ביתה.

Bavli, Moed Katan 21b
Our Rabbis have taught: A mourner is prohibited in melacha for the first three days, and even if he is a person who is supported by tzedaka. From that time and going forward, he can do melacha privately in his home and a woman can weave with the spindle.

The Rabbis here understand that the first three days are more stringent than the remaining four as related to the prohibition of melacha. They go so far as to demand that even a person who is unable to support themselves may not work. What is different about the first three days?

There are two different approaches to the unique nature of the first three days. One is based on another passage in the Bavli about the emotional intensity of the beginning of the week of shivva. The second emerges from a more mystical texts from the Yerushalmi¹.

The Bavli:

תלמוד בבלי מסכת מועד קטן דף כז עמוד ב

אַל תִּבְכּוּ לְמֵת וְאַל תָּנֻדוּ לוֹ (ירמיהו כב:י) אַל תִּבְכּוּ לְמֵת יותר מדאי וְאַל תָּנֻדוּ לוֹ לו יותר מכשיעור.

הא כיצד? שלשה ימים לבכי, ושבעה להספד, ושלשים לגיהוץ ולתספורת.

מכאן ואילך אמר הקדוש ברוך הוא אי אתם רחמנים בו יותר ממני 

Bavli, Moed Katan 27b

Weep not for the dead, neither bemoan him (Jeremiah 22:10) Weep not for the dead excessively. Neither bemoan him more than the [appropriate] measure of time. How so? Three days for weeping, and seven for eulogizing, and thirty for [the prohibition against] ironing and for [the prohibition against] cutting hair. From this point forward the Holy Blessed One says: Do not be more merciful with the deceased more than I am.

The idea that the first three days are more intense and are, therefore, set aside for “weeping – בכי” is both prescriptive and descriptive. There are normative implications of the fact that the rabbis understand that these days are specifically for weeping. Rabbeinu Yerucham quotes the Raavad as explaining the stringency of the first three days regarding melacha as based on this idea:

רבינו ירוחם – תולדות אדם וחוה נתיב כח חלק ב
וכתב הראב”ד וטעם שאפילו העני אסו’ במלאכה בשלשה ימים הראשונים משום דאמרו חז”ל שלשה לבכי ואם יעסוק במלאכה נמצא מתעצל בבכי.

Rabbeinu Yerucham, Toldot Adam v’Chava, Netiv 28, Chelek 2 (233a)

And the Raavad wrote that the reason that even the poor person is prohibited from doing work for the first three days is that the Rabbis said (Moed Katan 27b), “Three days for weeping.” And if the mourner would get involved with work he would be lazy in his fulfillment of the requirement of weeping.

Here, Rabbeinu Yerucham understands that the notion of “three days for weeping” requires a fence for its protection. He claims that the reason for the stringency of the prohibition of melacha in the first three days is in order to ensure that the mourner is able to weep appropriately. 

The Yerushalmi:

Here we encounter a fascinating, mystical text from the Yerushalmi that plays a pivotal role in several different areas of Hilkhot Aveilut.

תלמוד ירושלמי (וילנא) מסכת מועד קטן פרק ג הלכה ה
ר’ אבא בריה דר’ פפי ר’ יהושע דסיכנין בשם ר’ לוי
כל תלתא יומין נפשא טייסא על גופא סבירה דהיא חזרה לגביה
כיון דהיא חמייא דאישתני זיויהון דאפוי היא שבקא ליה ואזלה לה.

Yerushalmi, Moed Katan, Chapter three Halakha five

R. Abba the son of R. Pappi and R. Yehoshua of Sichnin in the name of R. Levi said, “During the first three days the soul hovers over the body as she thinks that she will return to it. Once she [the soul] sees that the shining of the face has changed she [the soul] takes leave and departs.

The Beit Yosef quotes both of these approaches in explanation of the Tur in 380:2². If we take the Yerushalmi at face value, there does appear to be a common Halakhic case that highlights the difference. If a person only hears about the passing of a loved one after burial and shivva but still before the conclusion of thirty days (שמועה קרובה), do they need to be as stringent regarding the first three days?

According to the Bavli and Rabbeinu Yerucham, it would seem obvious that the same weight be applied to the first three days. However, if we were to operate with the understanding of the Yerushalmi, then the soul of the person who has passed should have already departed and there would no longer be a reason for greater stringency regarding those first three days³.

I am not certain that we are meant to work with this passage in the Yerushalmi in such a literal fashion, but it does appear to be integrated into the normative flow of Halakha. One of the challenges of Hilkhot Aveilut is to strive to understand the mystical ideas that are embedded in the laws and be able to appreciate that there is often more going on than meets the eye.

There is often a desire on the part of those of us who lean toward the rationalist side of life to imagine that we can subtract out the mystical components from Halakha. That is simply a fool’s errand. There are some Rabbis who are more or less influenced by the mystical side of our tradition, but it is simply impossible to silo out those two world-views. Rabbi Yosef Karo, arguably the most significant Halakhic figure in the history of Halakha was deeply immersed in the world of Kabala.

There are times when I feel some discomfort about this reality, but there is also a sense to which this gives me great comfort. I understand that Halakha is much bigger than any given moment or any particular decision that must be made. Halakha can be understood as connected to the spiritual harmony of the universe. When it comes to people passing from this world to the next, there is a sense that we are a bit closer to those ways of thinking and being in the world.

1. See also Zohar ויקהל קצ”ט ע”ב beginning with the phrase שלשה ימים ושלשה לילות where Jonah’s time in the belly of the fish is compared to the first three days after someone passes.
2. The Perisha (380:2) also quotes both the Yerushalmi and the Bavli together with Rabbeinu Yerucham. The בדי השלחן in סימן שפ in סקי”ב he also brings both ideas.
3. The Chatam Sofer asked this very question and said in שו”ת חתם סופר חלק ב (יורה דעה) סימן שמו:

   (ה) בכ”מ פ”ה ה”ח אמת כן הוא בירושלמי ורמב”ן וטור אבל לפי זה בשמע שמוע’ קרובה נהי דיום שמועה הוא יום מר כבפניו ומושך ז’ ימים אחריו מ”מ לענין חומר ג’ ימים היה לן להקל דכבר תו נפשא לא טייסא אגופא ולא מצינו מי שמחלק בזה.

   He concludes, simply, “And we have not seen anyone make this distinction.” In the שאול יוסף דעת v.2 on שפ he does appear to pasken in a lenient fashion in this case. See חזון עובדיה אבילות ח”ב regarding the prohibition of melacha, עמ’ קאו-ז in הע’ א.