Surah Yunus 10:19

وَمَا كَانَ ٱلنَّاسُ إِلَّآ أُمَّةً وَٰحِدَةً فَٱخْتَلَفُوا۟ ۚ وَلَوْلَا كَلِمَةٌ سَبَقَتْ مِن رَّبِّكَ لَقُضِىَ بَيْنَهُمْ فِيمَا فِيهِ يَخْتَلِفُونَ

And mankind was not but one community [united in religion], but [then] they differed. And if not for a word that preceded from your Lord, it would have been judged between them [immediately] concerning that over which they differ.

Translation: Saheeh International

Tafsir

Mankind was but one community following one religion that is submission to the One God from the time of Adam to the time of Noah; but it is also said that this was the case from the time of Abraham to that of ‘Amr b. Luhayy; …

Excerpt from Tafsir al-Jalalayn, commentary on 10:19, via Quran.com. The reader has the full commentary and 9 more tafsirs.