Surah Al-A'raf 7:90

وَقَالَ ٱلْمَلَأُ ٱلَّذِينَ كَفَرُوا۟ مِن قَوْمِهِۦ لَئِنِ ٱتَّبَعْتُمْ شُعَيْبًا إِنَّكُمْ إِذًا لَّخَـٰسِرُونَ

Said the eminent ones who disbelieved among his people, "If you should follow Shuʿayb, indeed, you would then be losers."

Translation: Saheeh International

Tafsir

Said the council of those of his people who disbelieved that is some said to others ‘Verily if la-in the lām is for oaths you follow Shu‘ayb you shall indeed be losers’.

Excerpt from Tafsir al-Jalalayn, commentary on 7:90, via Quran.com. The reader has the full commentary and 9 more tafsirs.