Morgan Wade had Teddi Mellencamp on her mind while performing onstage ... pausing between songs at L.A.’s El Rey Theatre to talk about her friend's health woes.

The emotional moment was caught on camera -- onstage, Morgan asked the audience to pray after the show for the 'RHOBH' star as she recovers from brain tumor surgery. But after some encouragement from a fan, Morgan led a powerful group prayer with the crowd on the spot.

Morgan, who met Teddi through her 'RHOBH' pal Kyle Richards, asked God to watch over Teddi, praising her as an amazing individual and loving mother -- before the crowd joined in, ending the prayer with a heartfelt "Amen."

MW shared that Teddi would’ve totally been there cheering her on if it weren’t for surgery -- but made it clear she hadn’t lost her humor amid all her pain, recalling how Teddi roasted her from her hospital bed when she went to visit.

It’s a positive update -- especially after Teddi’s sister Justice described watching her endure the "horrific" pain.

As we reported, docs discovered multiple tumors on Teddi's brain after she sought medical help for weeks of debilitating headaches.