فَدَارِهِمْ مَا دُمْتَ فِي دَارِهِمْ
Treat them tactfully while you remain in their house.
Mustawfa retains full verbal identity while the two occurrences belong to different word classes. In “fādārihim … fī dārihim,” the first expression is an imperative with its object, whereas the latter contains the noun dār (“house”) in a prepositional phrase.
Analysis requires identifying grammatical function in each position; graphic resemblance alone cannot tell us which occurrence is verbal and which nominal.