(footnote : I have seen baalei Nigleh asking on this, and with a great shturem, hayitochen etc etc. But there is an explicit reference in nigle as well, and this is in the Yerushalmi bikurim chap 3, halacha 3: “and Hevaya in His Holy chamber, this refers to R’ Yitzchak the son of Rabbi Elazar in the beis midrash of Kisarin.)
Needs further explanation.