(Glorified and Exalted is He high above what they say!) meaning these idolators who transgress and do wrong when they claim that there are other gods besides Him.
عُلُوّاً كَبِيراً
(high above) means, far above. He is Allah, the One, the Self-Sufficient Master, Whom all creatures need. He begets not, nor was He begotten, and there is none comparable or coequal unto Him.
Ma'arif al-Qur'an
Mufti Muhammad ShafiOn ayahs 42–43
Commentary
According to the proof of Tauhid (the Oneness of Allah) given in the verse: إِذًا لَّابْتَغَوْا إِلَىٰ ذِي الْعَرْشِ سَبِيلًا (then they would have found out a way to the Lord of the Throne - 42), Allah alone is the creator, owner and master of the entire universe. The argument is if it was not so and He had other partners in this godhead, differences would have necessarily emerged among them. And, in the eventuality of a difference, the whole universal system would have gone to ruins - because, ever abiding peace among them is habitually impossible. Though, this argument has been enunciated here in a prohibitive manner, but there are books of Scholastic Theology (` Ilm al-Kalam) where the logical rationale behind this argument has also been described in great details. The learned may consult these at their discretion.
Tazkirul Quran
Maulana Wahiduddin KhanOn ayahs 39–43
The injunctions given in the above verses come under the heading of ‘wisdom’ (hikmah). The meaning of ‘wisdom’ here stands for the firm reality, the sound truths of life. It is on the foundations of these realities that the healthy life is built. A human society devoid of them can expect little else but annihilation both in the present and in the next life. The narration of the above-mentioned advice begins with the Oneness of God, or tawhid (verse 22) and finishes with the oneness of God (verse 39). This indicates that, for the foundation of all good deeds, man should believe in the one God. He should fear and love Him alone. The secret of a good life is concealed in the right relationship with God. If the relationship with God is not proper, no other thing can set right the affairs of human life. God is the beginning and the end of human life.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.