Some complete clauses convey a meaning very close to that of a single-word circumstantial modifier. A phrase such as ʿalā katifihi sayfun can describe Zayd's visible condition as he arrives, thereby performing the role of an attendant description.
When the syntax already supplies a natural circumstantial reading, wāw may become less necessary. This does not mean that every preposed prepositional phrase automatically is a ḥāl; the subject–predicate analysis and the referent of the pronoun must still be established.