What is the ruling on the yellow, odorless pus that exudes from the navel when the skin ulcerates, and is it true that pus is pure if it has no odor, and impure if it has an odor?

The yellow fluid emanating from festering wounds is called "pus," and it is ritually impure (najis). As for the fluid from sores (blisters/ulcers), there is a detailed explanation among the Shafi'is: if it has an odor, it is impure; if it has no odor, then its purity is apparent. Imam An-Nawawi stated that pus is impure by consensus, and similarly, altered fluid from sores is impure by agreement. However, unaltered fluid from sores is pure according to the madhhab.