Does impurity transfer from an impure body to the bed when sleeping on it if both are dry at that time? And does the bed remain pure if it was previously impure, and the body and clothes were purified before sleeping on it again while they are wet?

If an impure body is dry, and what touches it from the pure things is also dry, then the impurity does not transfer. Therefore, the bed in question has not become impure, as the impure body was dry. If you sleep on it afterward while your body or clothes are wet, it will not become impure as long as your body and clothes are pure, because a pure thing does not become impure by touching pure things.

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