וְהִנֵּ֨ה עָ֘לָ֤ה כֻלּ֨וֹ ׀ קִמְּשֹׂנִ֗ים כָּסּ֣וּ פָנָ֣יו חֲרֻלִּ֑ים וְגֶ֖דֶר אֲבָנָ֣יו נֶהֱרָֽסָה׃
看哪，遍地都長滿了荊棘，地面被蕁麻覆蓋，石牆也已坍塌。
Rashi
nettles חרלים. They are larger than thistles, and they are as sharp as thorns.
Rashi
and its stone fence had been torn down Thus, one who does not review his studies first forgets the beginnings of the chapters and at the end confuses the names of the Sages from this one to that one, thereby saying “unclean” for something that is clean and “clean” for something that is unclean, and he destroys the world.