"We lost a good one...What a legend," Keith says in the video. "Great guy, great entertainer, great singer. What a career. Rest in peace, Harold."
Harold's younger brother and fellow Statler Brothers co-founder Don Reid announced the passing of Reid on his website.
"He is and will always be loved by his family, friends and millions of fans," read the statement. "His singing, his songwriting and his comedy made generations happy. He has taken a piece of our hearts with him."
The Grammy-winning "Flowers on the Wall," written by Lew DeWitt, spent four weeks at No. 2 on the Billboard Hot Country Singles Chart in 1966. The song was later recorded by Nancy Sinatra. In 2000, Eric Heatherly scored a top 10 hit on the country charts with a cover of the song. The song was also famously featured in the 1994 film Pulp Fiction.
Keith released his latest song, "What's Up Cuz," in April 2020.