Midrash su Proverbi 23:10

Whence is it derived that if one removes the bounds of the tribes he transgresses a negative commandment? From (Proverbs 22:28) "Do not remove the long-standing boundary marker (which your forefathers have established.") Whence is it derived that if one confuses the words of R. Eliezer with those of R. Yehoshua, and vice versa, pronouncing clean, unclean, or unclean, clean — that he transgresses a negative commandment? From "You shall not move back the boundary marker of your neighbor." Whence is it derived that one who sells the burial plot of his fathers transgresses a negative commandment? From "You shall not move back the boundary marker of your neighbor." I might think that this were so even if no one were ever buried there; it is, therefore, written "in your inheritance that you shall inherit"