The maaseh behind it
Reb Pinchas ben Yair, the shver of Reb Shimon bar Yochai, was known for his tremendous tzidkus and his perishus. Once, on his way to be podeh shvuyim, he asked the Ginai River to split so he could cross — and the river split before him. His kever in Tzfas was revealed by the Arizal, but they were never able to build a grand tziyun over it: Reb Pinchas asked in a chalom to remain in the same simplicity in which he lived. Al pi eidus, the cave runs all the way to the kever of his eidem, Reb Shimon, in Meron — and every erev Rosh Chodesh the tzaddikim buried in that cave rise up from there.