Surah Ash-Shu'ara, ayah 13

وَيَضِيقُ صَدۡرِي وَلَا يَنطَلِقُ لِسَانِي فَأَرۡسِلۡ إِلَىٰ هَٰرُونَ ١٣

Wayadīqu sadrī walā yantaliqu lisānī fa arsil ilā hārūn

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