Surah Al-Anbya — Ayah 105 (21:105)

English translation (Saheeh International)

And We have already written in the book [of Psalms]¹ after the [previous] mention² that the land [of Paradise] is inherited by My righteous servants.

1. Az-Zabūr can also mean "scriptures" in general.
2. i.e., the Torah. The "mention" may also refer to the original inscription with Allāh, i.e., the Preserved Slate (al-Lawḥ al-Maḥfūẓ).

Brief commentary

I had indeed written in the books I revealed unto the messengers, after I had written it in the Preserved Tablet, that the earth would be ruled by the pious, obedient servants of Allah: they are the nation of Muhammad peace be upon him.