Bava Batra 144B

מתני׳ אחין השותפין שנפל אחד מהן לאומנות ⁠– נפל לאמצע. חלה ונתרפא ⁠– נתרפא משל עצמו.

Mishnah: With regard to brothers who were also partners, and it occurred that one of them was summoned to public service, which is assessed per family, he was summoned from the middle, i.e., the profits or expenses of his service are divided among them. If one of the brothers became sick and sought treatment, the cost of the treatment is paid from his own resources.

גמ׳ תנא: האי אומנות ⁠– לאומנות המלך. תנו רבנן: אחד מן האחין שמינוהו גבאי או פולמוסטוס; אם מחמת האחין ⁠– לאחין, אם מחמת עצמו ⁠– לעצמו.

Talmud: A baraita states: This service mentioned in the Mishnah is referring to forced imperial service, but if one of the brothers engaged in a trade of his own volition, the profits are his alone. A baraita states (Tosefta 10:5): In the case of one of the brothers who was appointed as a tax collector or a military commander [polmustos], a position with the potential for profit, if he was appointed on account of all the brothers, as the procedure was to impress a representative from each family for this purpose, any profit accrues to all the brothers. If he was appointed on account of himself, the profit accrues to himself.

אם מחמת אחין לאחין ⁠– פשיטא! לא צריכא, דחריף טפי; מהו דתימא: חורפיה גרים ליה, קא משמע לן.

The Talmud asks: Isn’t it obvious that if he was appointed on account of all the brothers, then the profit accrues to all the brothers? The Talmud responds: No, it is necessary to state this halakha in a case where the brother appointed was sharper, i.e., more capable, than the other brothers. Lest you say that his sharpness caused him to be selected for the position, and he should receive all the profits, the baraita teaches us that his talent notwithstanding, since he was selected as a representative of the family, the profit accrues to all the brothers.