Surah Al-Muzzammil, ayah 8

73:8

وَٱذۡكُرِ ٱسۡمَ رَبِّكَ وَتَبَتَّلۡ إِلَيۡهِ تَبۡتِيلٗا ٨

Wadhkurisma rabbika watabattal ilayhi tabtīlā

And remember the name of your Lord and devote yourself to Him with [complete] devotion.