Back in the the early 1970s, when Elton John was a young unknown, he opened a few shows for his idol Leon Russell. Decades later in 2010, when John was a superstar and Russell had largely receded from the popular consciousness, they teamed up for a duet album called The Union, with John’s aim being to renew Russell’s recognition.

Russell passed away in his sleep last night, and now John has posted a brief tribute on Facebook along with a photo of the two in the studio together. “My darling Leon Russell passed away last night,” he writes. “He was a mentor, inspiration and so kind to me. Thank God we caught up with each other and made ‘The Union’. He got his reputation back and felt fulfilled. I loved him and always will.”