Dolly Parton’s sister has fans on edge — revealing online the music legend ain’t doing too good — and she’s begging for prayers.

Not long after Dolly axed 6 shows from her Vegas residency due to health reasons, her sister Freida hit Facebook Tuesday … saying the 79-year-old legend still isn’t at her best, and pleading with fans worldwide to be “prayer warriors” for the country legend.

Freida — who said she’d been up all night praying — reassured fans that Dolly’s strong and deeply loved … and with the world’s prayers lifting her up, she believes her sister’s gonna be just fine.

She wrapped the post with, “Godspeed, my sissy Dolly. We all love you!” — alongside a powerful shot of Dolly herself in prayer.

Of course, fans didn’t need to be told twice … Freida’s post was flooded with prayers and well-wishes … and truth be told, folks have been worried ever since Dolly said she needed some procedures and postponed her Las Vegas residency from December to September of next year.