Surah Al-Hijr — Ayah 99 (15:99)
وَٱعۡبُدۡ رَبَّكَ حَتَّىٰ يَأۡتِيَكَ ٱلۡيَقِينُ ٩٩
English translation (Saheeh International)
And worship your Lord until there comes to you the certainty [i.e., death].
Brief commentary
Go on worshipping your Lord and continue doing so as long as you live until death comes to you in that state.