Bava Metzia 80B

שש עשרה שעורים ⁠– חייב. הא שלשת קבין ⁠– פטור! תרגמה אביי: במחיקתא.

16 se’a of barley, he is liable. This indicates that if he added only 3 kav, i.e., half a se’a, he is exempt. Abaye interpreted the baraita as referring to smoothed-over barley, a precisely measured load, where the volume of the barley was not measured with heaped measuring utensils, but leveled flat. Consequently, it is roughly a se’a less than the usual amount.

תנו רבנן: קב לכתף, אדריב לעריבה. כור לספינה, שלשת כורים לבורני גדולה.

§ A baraita states: A kav is too large an addition for a porter, and therefore if the porter is injured by the additional weight, the owner must pay him. An adriv, half a kor, is too large an addition for a small boat [areiva]; a kor is too large an addition for a regular boat; 3 kor is too large an addition for a large ship [burnei].

אמר מר: קב לכתף. אם איתא דלא מצי ביה בר דעת הוא, לשדיה! אמר אביי: בשחבטו לאלתר. רבא אמר: אפילו תימא בשלא חבטו לאלתר, לא צריכא אלא לאגרא יתירא. רב אשי אמר: הוא סבור חולשא הוא דנקיט ליה.

The Master said: A kav is too large an addition for a porter. The Talmud asks: If it is so, that he cannot withstand this load, the porter is a sensible person; let him throw it off and avoid injury. Abaye said: This is referring to a case where the load knocked him down immediately, before he could remove it from his back. Rava said: Even if you say that it is referring to a case where it did not knock him down immediately the baraita is not difficult, as it is necessary only with regard to the extra pay that he can demand for this addition. Rav Ashi said: Even if the porter is a sensible man, perhaps he thought it was a momentary weakness that seized him and did not realize that the load itself was excessive.