[If one said to another,] “I am selling you a beis kor of earth, as measured by a rope,” [if] he gave [even] the slightest amount less he must deduct; [if] he gave [even] the slightest amount more he must give back. If he said, “whether less or more,” even if he gave a quarter-kav less per seah or a quarter-kav more per seah, it becomes his. [If it was] more than this, he should make a reckoning. What does he give back? Money. But if [the seller] prefers, he gives him back the land. Why did they say that he gives back money? To improve the position of the seller. So that if there remained an area of nine kavs in the field, or half a kav in a garden —- or a quarter-kav according to R' Akiva —- he may give him back the land. Moreover, it is not only the quar-ter-kav that he gives back, but all the excess.