“Wa-mā naqamu illā an aghnāhumu Allāhu wa-rasūluhu min faḍlihi”
“They resented only that God and His Messenger had enriched them out of His bounty.” (al-Tawbah 9:74, excerpt)
“God and His Messenger” are mentioned together, but “faḍlihi” carries a singular pronoun. Divine bounty is ascribed ultimately to God; the Messenger is involved in communicating and administering what God grants. The pronoun accordingly returns to God.
One must not infer that a pronoun following two coordinated nouns always requires a dual form. The relevant referent is determined by meaning and context, not by mechanically counting adjacent nouns.