Surah Al-Kahf 18:14

وَرَبَطْنَا عَلَىٰ قُلُوبِهِمْ إِذْ قَامُوا۟ فَقَالُوا۟ رَبُّنَا رَبُّ ٱلسَّمَـٰوَٰتِ وَٱلْأَرْضِ لَن نَّدْعُوَا۟ مِن دُونِهِۦٓ إِلَـٰهًا ۖ لَّقَدْ قُلْنَآ إِذًا شَطَطًا

And We bound [i.e., made firm] their hearts when they stood up and said, "Our Lord is the Lord of the heavens and the earth. Never will we invoke besides Him any deity. We would have certainly spoken, then, an excessive transgression.

Translation: Saheeh International

Tafsir

And We strengthened their hearts to enable them to speak the truth when they stood up before their king who had commanded them to prostrate to idols and said ‘Our Lord is the Lord of the heavens and the earth. …

Excerpt from Tafsir al-Jalalayn, commentary on 18:14, via Quran.com. The reader has the full commentary and 9 more tafsirs.