What is the chief role of “wajhuhu mubtasimun” in “dakhala Zaydun wa-wajhuhu mubtasimun”?

Supplementary Practice 7: Editing Expressions, Weighing Context and Rhetorical Critique

• A nominal circumstantial clause linked by pronoun and wāw
• The response to an oath introduced by wāw
• An unrelated vocative
• The direct object of entering