Quran 26:13 from Surah Ash-Shu'araa on Divine Marvels.
وَيَضِيقُ صَدۡرِي وَلَا يَنطَلِقُ لِسَانِي فَأَرۡسِلۡ إِلَىٰ هَٰرُونَ
English translation: And straitens my breast and not expresses well my tongue so send for Harun
Transliteration: wayadiqu sadri wala yantaliqu lisani fa-arsil ila haruna