Rod Stewart has abruptly canceled a pair of Las Vegas performances scheduled for this weekend.

The shows were originally supposed to take place tonight (May 29) and tomorrow night (May 30), but the plug was pulled just hours before the 81-year-old singer was scheduled to hit the stage. The concerts were part of Stewart’s Encore Shows, the latest of his evolving residencies at the Colosseum at Caesars Palace.

News of the cancellations began spreading after Ticketmaster removed both shows from their schedule. Fans who purchased tickets were soon sent emails with refund instructions. While there was initially no explanation given, a spokesperson for Stewart later offered the following statement to the Las Vegas Review Journal:

“Following his doctor’s advice, Rod Stewart has regretfully cancelled his performances at The Colosseum at Caesars Palace in Las Vegas on May 29 and 30, but is scheduled to return with shows beginning June 2.

“My apologies to my family of fans,” Stewart said. “I am on vocal rest as I recover from a sinus infection. I look forward to seeing you at a future show at Caesars Palace or on tour this summer.”

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By all accounts, Stewart seemed fine during his last performance, which took place on Wednesday night. The Rock & Roll Hall of Famer delivered a 19-song set at that concert, which marked the first show of his latest Las Vegas residency. Stewart’s first run of Encore Shows goes until June 6, with a second installment following in August. He also has his ongoing One Last Time tour taking place this summer.