And We made firm their hearts when they stood up and said, (18:14)

﴿وَرَبَطْنَا عَلَىٰ قُلُوبِهِمْ إِذْ قَامُوا فَقَالُوا رَبُّنَا رَبُّ السَّمَاوَاتِ وَالْأَرْضِ لَن نَّدْعُوَ مِن دُونِهِ إِلَٰهًا ۖ لَّقَدْ قُلْنَا إِذًا شَطَطًا﴾
[ الكهف: 14]

18:14 And We 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.

And I strengthened their hearts with faith and firmness on it, and to be patient in leaving one’s homeland for its sake, when they stood to proclaim their faith in Allah alone in front of the disbelieving king, and they said: The Lord I believe in and worship is the Lord of the heavens and earth.
I will never worship the gods you have falsely claimed besides Him.
I will have said an unjust and far-off statement if I worship others besides Him.

And We made their hearts firm and strong (with the light of Faith in Allah and bestowed upon them patience to bear the separation of their kith and kin and dwellings, etc.) when they stood up and said: "Our Lord is the Lord of the heavens and the earth, never shall we call upon any ilah (god) other than Him; if we did, we should indeed have uttered an enormity in disbelief.

phonetic Transliteration

Warabatna AAala quloobihim ith qamoo faqaloo rabbuna rabbu alssamawati waalardi lan nadAAuwa min doonihi ilahan laqad qulna ithan shatatan

Abdullah Yusuf Ali - Translation

We gave strength to their hearts: Behold, they stood up and said: "Our Lord is the Lord of the heavens and of the earth: never shall we call upon any god other than Him: if we did, we should indeed have uttered an enormity!

Safi-ur-Rahman al-Mubarakpuri

And We made their hearts firm and strong when they stood up and said: "Our Lord is the Lord of the heavens and the earth, never shall we call upon any god other than Him; if we did, we should indeed have uttered an enormity in disbelief.

Page 294 English transliteration