How life stories turned into Halachot - Mishnaic examples?

Question

The first Mishna in Brochos states:

מעשה ובאו בניו מבית המשתה אמרו לו לא קרינו את שמע אמר להם אם לא עלה עמוד השחר חייבין אתם לקרות

There was an incident where Rabban Gamliel’s sons returned very late from a wedding hall. They said to him, as they had been preoccupied with celebrating with the groom and bride: We did not recite Shema. He said to them: If the dawn has not yet arrived, you are obligated to recite Shema.

This looks weird to me that a minor incident made its way to the Mishnah - the Oral Law - straight without any discussion, arguments or review.

What is so exceptional, smart, necessary/obligatory in Rabbi's decision to write the story whole in the Mishnah for generations: R"G's sons, coming late, from a party, instead of just stating the conclusion (following) - "wherever the Sages say until midnight, the Mitzvah may be performed until dawn."? Would the Mishnah really be lacking any clarity or information had this story not be included?

Answer 1

In his commentary to that Mishnah Rambam writes:

והביא את המעשה הזה לחזק בו סברת רבן גמליאל ושהוא הורה כן

It brought this incident to strengthen the view of Rabban Gamliel and [to show] that he ruled this way [even in an actual case].

The significance of this perhaps becomes more apparent when considering the Talmud's analysis of this clause on 9a:

מעשה שבאו בניו וכו' ועד השתא לא שמיע להו הא דר"ג הכי קאמרי ליה רבנן פליגי עילווך ויחיד ורבים הלכה כרבים או דלמא רבנן כוותך סבירא להו והאי דקאמרי עד חצות כדי להרחיק אדם מן העבירה אמר להו רבנן כוותי סבירא להו וחייבין אתם והאי דקאמרי עד חצות כדי להרחיק אדם מן העבירה

IT ONCE HAPPENED THAT HIS SONS CAME HOME [LATE], etc. How is it that they had not heard before of this opinion of R. Gamaliel? — [They had heard], but they asked thus: Do the Rabbis join issue with you? For if so, where there is a controversy between an individual and a group, the Halachah follows the group. Or do the Rabbis agree with you [in substance], but they say: UNTIL MIDNIGHT, in order to keep a man far away from transgression? — He replied: The Rabbis do agree with me, and it is your duty [to recite the Shema']. But they say, UNTIL MIDNIGHT, in order to keep a man far from transgression.

(Soncino translation)

Thus, this case was an apparent exception. Normally if one tanna would disagree with the majority of tannaim, his view would be rejected. In this particular case, though, contrary to what might appear at first glance, the majority of Sages actually agreed to Rabban Gamliel in principle, and therefore in practice one should follow Rabban Gamliel's opinion if he has not yet said Shema. This is illustrated by showing that Rabban Gamliel's children followed his ruling in an actual case.