Bava Metzia 40A

וכן אמר רבה: השביחו לאמצע. אמר ליה אביי: מי דמי? התם, גדולים גבי קטנים ידעי וקא מחלי, הכא מי ידע דליחיל?

And likewise, Rabba says: They enhanced the property, and the profit goes to the middle. Abaye said to him: Are these matters comparable? There, in the case that the adult and minor brothers were together, the adults are aware that the minors exist and forgo payment for their effort on behalf of their younger brothers. Here, in the case of Mari bar Isak, was the older brother aware of the existence of the younger brother so that he could forgo payment for his labor?

אגלגל מלתא ומטא לקמיה דרבי אמי. אמר להו: גדולה מזו אמרו: שמין להם כאריס, השתא דידיה לא יהבינן ליה?

The matter continued to develop and came before R' Ami. He said to those who reported Rav Ḥisda’s ruling: The rabbis stated a more far-reaching halakha than that: In the case of relatives who tend to the property of a captive, the court appraises their work as one would appraise the work of a sharecropper. Although the property they tended did not belong to them at all, they receive wages for their labor. Why, then, is the ruling now, in the case of Mari bar Isak, that payment for labor on property that is his, we do not give him? Mari bar Isak should be reimbursed for his expenditures.

אהדרוה (הא) לקמיה דרב חסדא. אמר להו: מי דמי? התם ברשות נחית, הכא לאו ברשות נחית. ועוד: קטן הוא, ואין מורידין קרוב לנכסי קטן.

They returned and related this matter before Rav Ḥisda. Rav Ḥisda said to them: Are these matters comparable? There, in the case of the captive’s property, it was with authorization from the court that the relative descended to tend to the property. Here, it was without authorization that Mari bar Isak descended to tend to the property of his brother. And furthermore, Mari bar Isak’s brother was a minor when Mari inherited the property, and the court does not authorize a relative to descend and manage the property of a minor.