The pronoun in “fīh” refers to the Book, connecting the second statement with the first by reference. But a shared pronoun alone is not sufficient to establish complete connection. The decisive issue is the second clause’s reinforcing effect.
Two independent descriptions of the same referent can sometimes be coordinated. Conversely, a second sentence functioning as a particularly close restatement is better left uncoordinated. Shared reference, shared topic, and emphatic connection are distinct notions.