TORONTO -- Elton John told fans shortly before a Saturday night concert in Indianapolis that "with the heaviest heart" he would be postponing the show.

The U.K. musician posted on social media several hours before the event that he was "extremely unwell" and in no shape to perform.

And while John didn't offer further details, the decision came after Gladys Furnish -- the mother of his Toronto-born husband David Furnish -- died several days ago.

John confirmed his mother-in-law's death at a Toronto concert on Thursday, playing his song "Don't Let the Sun Go Down on Me" in her name.

The 72-year-old performer is in the midst of a farewell tour saying he plans to spend more time with his husband and children.

He says the postponed Indianapolis show will be rescheduled for March.

On Friday, Furnish posted a photo of his mother's wedding day on Instagram, saying she died peacefully with her sons by her side.

"Rest in peace Mum. You lived your life impeccably. I will never forget you. I promise to do my best to pass the gifts you gave to me on to my own beautiful sons," he wrote in the message.

This report by the Canadian Press was first published Oct. 27, 2019.