Temurah 27B

והאמר רבי ירמיה אקרקעות דחולין, ורבי יונה אמר אהקדשות, תרווייהו משמיה דרבי יוחנן אמרי: אונאה אין להן, ביטול מקח יש להם!

But didn’t R' Yirmeya say this ruling with regard to non-sacred lands, and R' Yona said it with regard to consecrated property, and both of them said it in the name of R' Yoḥanan: They are not subject to the halakhot of exploitation, in the case of a disparity of 1/6th. But they are subject to nullification of a transaction, in the case of a greater disparity. If so, according to the opinion of R' Yona, R' Yoḥanan maintains that when the disparity between the value and the payment is greater than 1/6th, the transaction is nullified by Torah law. But in that case, why would R' Yoḥanan rule here that only by rabbinic law is he required to calculate the difference and pay its value?

לעולם אביטול מקח, ואיפוך.

The Talmud answers: Actually, they disagree in a case of nullification of a transaction, i.e., more than 1/6th, and one should reverse attribution of the opinions; the opinion previously attributed to R' Yoḥanan is actually that of Reish Lakish, and the opinion attributed to Reish Lakish is the ruling of R' Yoḥanan.

ומי מצית אמרת איפוך? הניחא למאן דאמר אהקדשות, וכל שכן אקרקעות.

The Talmud asks: But how can you say that one should reverse the attribution of the opinions of R' Yoḥanan and Reish Lakish? This works out well according to the one who says that R' Yoḥanan holds that consecrated property is not subject to the halakhot of exploitation if the disparity between the value and the payment is 1/6th, but it is subject to nullification of the transaction if the disparity between the value and the payment is greater than 1/6th. According to this opinion, that of R' Yona, it is apparent all the more so that lands are subject to nullification if the disparity is greater than 1/6th.