Bava Batra 94A

נותן לו דמי חטין!

must give him the value of wheat of equal volume to the pebble that he removed. Had he not removed the pebble, the owner would have sold his wheat together with the pebble, all for the price of wheat. Accordingly, the removal of the pebble effectively caused the owner a small loss. It is apparent from this ruling that when selling produce, a buyer accepts upon himself that a quantity of dirt may be mixed in.

קטנית ⁠– רובע, עפרורית ⁠– פחות מרובע.

The Talmud answers: With regard to legumes, one accepts 1/4th-kav per se’a, but with regard to dirt, he accepts less than 1/4th-kav.

ועפרורית ⁠– רובע לא?! והא תניא: המוכר פירות לחברו, חטין ⁠– מקבל עליו רובע קטנית לסאה. שעורים ⁠– מקבל עליו רובע נישובת לסאה. עדשים ⁠– מקבל עליו רובע עפרורית לסאה.

And is it so that he does not accept 1/4th-kav of dirt? But isn’t it taught in a baraita: With regard to one who sells produce to another, if he sells him wheat, the buyer accepts upon himself that 1/4th-kav of legumes may be present in each se’a of wheat purchased. When purchasing barley, he accepts upon himself that 1/4th-kav of chaff may be present in each se’a purchased. When purchasing lentils, he accepts upon himself that 1/4th-kav of dirt may be present in each se’a purchased.

מאי, לאו הוא הדין לחטים ולשעורין? שאני עדשים, דמיעקר עקרי להו.

The Talmud asks: What, is it not that just as the baraita rules with regard to lentils, the same is true for wheat and for barley? The Talmud answers: No, lentils are different, because they are dug up from the ground and dirt can easily get mixed in. Lentils often contain a higher percentage of dirt than do wheat and barley, which are harvested rather than dug up.