Will Allah expose His believing servant as a trial for him, and what is the ruling on one who spies on his Muslim brother's phone to uncover his secrets and expose him?

The calamities and tribulations that befall a believer may be a test, or an expiation for his sins, and an elevation of his status. They may also be a punishment for a sin he committed, or rejoicing at a Muslim's misfortune, or exposing him. For whoever searches for the faults of Muslims, Allah will search for his faults and expose him. And it is not permissible to search for the faults of Muslims by spying on them.