i have a huge prayer plant with spider mites and would like to know a cure for this please . thank you from john.

Spray the whole thing down with mild soapy water (cover soil) or fill up about an inch of rubbing alcohol (Isopropyl) and the rest with tepid water. Make sure you get every inch including the back of the leaves and also wipe the surrounding area where the plant sits just in case. Keep any direct sun off the plant while drying.
Spray at least once a week for a couple weeks or so until gone, but keep an eye out. If you missed any, they can return.If any other plant or plants are nearby, check them for spidermites as well.