﴿ وَرَبَطْنَا عَلَىٰ قُلُوبِهِمْ إِذْ قَامُوا۟ فَقَالُوا۟ رَبُّنَا رَبُّ ٱلسَّمَٰوَٰتِ وَٱلْأَرْضِ لَن نَّدْعُوَا۟ مِن دُونِهِۦٓ إِلَٰهًۭا ۖ لَّقَدْ قُلْنَآ إِذًۭا شَطَطًا ﴾

“and endowed their hearts with strength, so that they stood up and said [to one another]: "Our Sustainer is the Sustainer of the heavens and the earth. Never shall we invoke any deity other than Him: [if we did,] we should indeed have uttered an enormity!”

Please check ayah 18:16 for complete tafsir.