Years before Jacob Lusk became a finalist on "American Idol" ... he formed a very special relationship with the one and only Nate Dogg -- a bond, TMZ has learned, that formed in an L.A. gospel choir.
Sources tell TMZ, Jacob auditioned for the gospel group called "InNate Praise" in 2007 -- formed by Nate himself -- and he ended up landing the part ... and we're told, it was the beginning of a beautiful friendship.
According to sources, Jacob and Nate's relationship blossomed over the next two years ... as Jacob performed with the group at churches around L.A. County.
In the video -- shot back in 2007 -- Nate and Jacob are both hanging out in Nate's studio in North Hollywood. Earlier today, Jacob tweeted the following about Nate's death:
As we previously reported, Nate passed away yesterday -- and his family believes his death was caused by complications stemming from two strokes he suffered over the last few years.