Empty Garden by Paul McCartney

Lennon and John were good friends, and in 1974, Lennon appeared on John's single cover of "Lucy in the Sky with Diamonds", the B-side of which was Lennon's "One Day at a Time". The pair later collaborated on "Whatever Gets You thru the Night" which appeared on Lennon's Walls and Bridges album. Lennon agreed to appear in concert with Elton if "Whatever Gets You thru the Night" became a #1 single, which it did. On Thanksgiving Day, 1974, Lennon and John performed these two songs along with "I Saw Her Standing There". This would be Lennon's last live performance. The song title "Empty Garden" refers to the huge pile of flowers left behind by mourners outside The Dakota, John's home in New York City, near the site where he was assassinated.

When Lennon's son Sean was born in 1975, Elton was made godfather.
After Lennon's death, Elton was concerned that a tribute song to the late Beatle would be "clumsy" – until he saw Taupin's lyrics. The lyric "Can't you come out to play?" may refer to Lennon's song "Dear Prudence".

Elton John wrote and recorded an earlier instrumental tribute to Lennon, "The Man Who Never Died", which was issued as the B-side of "Nikita" in 1985 and eventually included as a bonus track on the remastered reissue .

Here is Elton Johns release:  https://www.youtube.com/watch?v=x8ctAXUsf1E