Pete Davidson Says Bob Saget Helped Him Through Mental Struggles

Tributes have been pouring in about Bob Saget, and how he touched so many lives, but few are as poignant as Pete Davidson's .. who says Bob stepped up for him during some pretty dark times.

Pete does not hop on social media -- period, but he made an exception for Bob, whom he called "one of the nicest men on the planet."

Pete wrote, "When I was younger and several times throughout our friendship he helped me get through some rough mental health stuff."

But, it wasn't just a "Hey, how ya doin'" call. Pete says Bob was genuinely concerned and wanted to help ... "He stayed on the phone with my mom for hours trying to help in anyway he can -- connecting us with doctors and new things we can try. He would check in on me and make sure I was okay."

It's one of a slew of tributes to Bob. TMZ broke the story, he died Sunday in an Orlando hotel room at age 65.