For the source text click/tap here: Bava Kamma 89
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When Rav Pappa and Rav Huna, son of Rav Yehoshua, came from the study hall of Rav they said: We learned a source for the ordinance of Usha in the mishna (87a): With regard to a slave or a married woman, an encounter with them is disadvantageous, since one who injures them is liable.
Rather, it must be that the mishna is discussing a case where she does not have usufruct property of which she can sell the future rights. So too, there is no source from the mishna for the ordinance of Usha, as the mishna is discussing a case where she does not have usufruct property to sell.
The takanot of Usha formed the basis of some 7 ordinances which we explore, as well as following the footsteps of the Sanhedrin from Jerusalem to Yavneh to Usha.