Surat Az-Zukhruf - سورة الزخرف

وَجَعَلَهَا كَلِمَةً بَاقِيَةً فِي عَقِبِهِ لَعَلَّهُمْ يَرْجِعُونَ

Muhsin Khan: And he made it [i.e. La ilaha ill-Allah (none has the right to be worshipped but Allah Alone)] a Word lasting among his offspring (True Monotheism), that they may turn back (i.e. to repent to Allah or receive admonition).