Surah Al-Waqi'ah, ayah 23

56:23

كَأَمۡثَٰلِ ٱللُّؤۡلُوِٕ ٱلۡمَكۡنُونِ ٢٣

Ka amthālil-lu'luw'il-maknūn

The likenesses of pearls well-protected,