What is the inserted “wa-llāhu yaʿlamu ṣidqa al-niyyāt” in the ongoing clause?

Supplementary Practice 16: Observing the Sky, Evidential Scope and Rhetorical Precision

• Necessarily a reinforcing circumstantial clause
• A parenthetic clause; the main predication survives without it
• The only predicate of inna
• A linking pronoun