Surah Ash-Shu'ara, Verse 13

وَيَضِيقُ صَدۡرِي وَلَا يَنطَلِقُ لِسَانِي فَأَرۡسِلۡ إِلَىٰ هَٰرُونَ١٣

wayaḍīqu ṣadrī walā yanṭaliqu lisānī fa-arsil ilā hārūna

And that my breast will tighten and my tongue will not be fluent, so send for Aaron.