Al Quddus

Allah Subhanuta'ala said.

يُسَبِّحُ لِلَّهِ مَا فِى ٱلسَّمَـٰوَٰتِ وَمَا فِى ٱلْأَرْضِ ٱلْمَلِكِ ٱلْقُدُّوسِ ٱلْعَزِيزِ ٱلْحَكِيمِ 

Whatever is in the heavens and whatever is on the earth ˹constantly˺ glorifies Allah—the King, the Most Holy, the Almighty, the All-Wise. [Al Quran 62:1]

 The Messenger of Allah (ﷺ) used to recite in his bowing and prostration: ""‏سبوح قدوس رب الملائكة والروح‏" [You are the Most Glorious. The Most Holy. You the Rubb of the angels and of Jibril. [Muslim].

Az-Zubair reported God’s messenger as saying that no morning comes to mankind without a crier calling, سَبِّحُوا الْمَلِكَ القدوس “Glorify the Kind, the Holy.”

Tirmidhi transmitted it. [Mishkat al-Masabih 2305]

Ubayy b. Ka'b said that when God’s Messenger gave the salutation in the witr he said, سُبْحَانَ الْمَلِكِ الْقُدُّوسِ “Glory be to the King most holy.” [Mishkat al-Masabih]

"Subhan" emphasizes the glorification of Allah's perfection and goodness, while "Quddus" emphasizes Allah's holiness and purity, and His separation from His creation.