A Holy Place in the World to Come
Yosef, the son of Rebbe Yehoshua, was sick and temporarily expired (Bava Basra 10b). During that brief lapse, he was given a glimpse of the World to Come.
Bava Basra 10
Your Loss Is Your Gain
The Gemara (Pesachim 87b) records a conversation that Hashem had with Hoshea HaNavi that is not mentioned at all in Tanach. Tosfos and Rashi both explain, however, how this conversation is alluded to in the verses.