What is the meaning of pessimism (tashā’um)? What is its criterion (ḍābiṭ)? And is fearing a cause that Allah has not made a cause for harm considered pessimism, such as fearing visiting a hospital out of dread of death, even though the visit is not a cause for death?

The blameworthy pessimism in Islamic law is that which causes a person to turn back or proceed based on it. However, mere thoughts, whispers, or feelings of fear, as long as no action results from them, are permissible. If a person refrains from doing something due to a feeling of pessimism, then this is tatyir (superstitious belief in omens) and a minor shirk (definition) (polytheism); because he relied on a cause that the Lawgiver did not make a cause. This has no relation to fear of a realistic matter like poor service. Sheikh Ibn ‘Uthaymeen mentioned that tatyir is a minor shirk because it is reliance on a cause that Allah did not make a cause, and it weakens reliance on Allah.