وَتَمَّتْ كَلِمَتُ رَبِّكَ صِدْقًا وَعَدْلًا ۚ لَّا مُبَدِّلَ لِكَلِمَـٰتِهِۦ ۚ وَهُوَ ٱلسَّمِيعُ ٱلْعَلِيمُ
Wa tammat Kalimatu Rabbika sidqanw wa 'adlaa; laa mubaddila li Kalimaatih; wa Huwas Samee'ul 'Aleem
The word of your Lord is complete in truth and justice. None can alter his words, and he is the All-Hearing, the All-Knowing.
Truth and justice divide the work between them, and the early commentators read the pair as covering two things a revelation does: it reports truthfully and it commands justly. The sentence lands between a question about seeking some judge besides God and a warning about the majority who follow guesswork, so its claim is one of stability, a word that stays fixed while human opinion moves.