Werner Herzog did not save Joaquin Phoenix in a literal or life-threatening sense. However, there is an interesting backstory related to the two of them that might be the source of this question.
Joaquin Phoenix and Werner Herzog worked together on the film “I’m Still Here” (2010), which was directed by Casey Affleck and starred Joaquin Phoenix. The film was a mockumentary that blurs the lines between reality and fiction, as Joaquin Phoenix embarked on a bizarre and controversial public performance art project, which involved him acting erratically and announcing his retirement from acting to pursue a career in rap music.
Werner Herzog had a cameo in the film, playing himself, and he offered a memorable scene where he gives philosophical advice to Joaquin Phoenix’s character. While the film itself was a staged performance and not a real-life rescue, it did lead to some speculation and confusion among viewers who were unsure whether Phoenix’s behavior was genuine or part of the film’s elaborate ruse.