Tosefta do Diwrej ha-jamim II 26:12

Rabbi Menachem son of Rabbi Yosei says, cities surrounded by a wall are more holy than the Land of Israel because lepers are sent out from inside of them, and their houses are [sold in] perpetuity ("צמות", see Zar Zahav here) inside of them after twelve months, and a corpse may be carried around inside of them as long as they desire, [but once] it is taken outside [the walls], they cannot bring it back in. And thus it says (2 Chron. 26:23), "And Uzziah was laid to rest with his fathers, and they buried him with his fathers, in the burial field of the kings, for they said, 'He is a leper.' And Yotam his son ruled in his place." [Returning to the theme of the previous section,] Rabbi Shimon says, just as there are no [zavim], zavot, niddot, or women after childbirth that may enter the Temple Mount, so too that which they lie on and that which they sit on [may also not enter the Temple Mount].