What is the trial of life and death mentioned in the supplication?

The meaning of fitnah is tribulation and trial, and its origin in the Arabic language is examination and testing. Then, it became used for any matter where the test reveals its negativity. It is said, "The man fattana (was tried), yaftinu (is being tried), futūnan (a trial)," when he falls into fitnah and transforms from a good state to a bad one.