Quran 20:27 from Surah Taa-Haa on Divine Marvels.
وَٱحۡلُلۡ عُقۡدَةٗ مِّن لِّسَانِي
English translation: And untie (the) knot from my tongue
Transliteration: wa-uh'lul uq'datan min lisani