Various online and written sources claim that various chassidic rabbis referred to Korah as "our holy grandfather". Some of these sources are mustered here, but they're all very secondary sources.
Can anyone point to a more primary source for a rebbe who made this comment? (Eg written by the rebbe themeselves, or by a follower? At least something better than a modern drashah which just mentions in passing, "And so-and-so used to say...")