The pair sang its duet Real Love during Gray's Smooth Summer Jazz 2015 set.
Smiling Brown thanked fans for their support and prayers as he left the stage.
Meanwhile, Bobbi Kristina's boyfriend Nick Gordon has visited her grave for the first time.
Reports suggest Gordon, who was banned from the 22 year old's funeral by family members, including her father, flew to New Jersey on 17 August (15) and took time to visit his late girlfriend's grave at Fairview Cemetery in Westfield.
Gordon has been accused of wrongful death by Bobbi Kristina's conservator.
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