Al-Baqarah 2:213

Kana annasu ommatan wahidatanfabaAAatha Allahu annabiyyeena mubashshireenawamunthireena waanzala maAAahumu alkitaba bilhaqqiliyahkuma bayna annasi feemaikhtalafoo feehi wama ikhtalafa feehi illa allatheenaootoohu min baAAdi ma jaat-humu albayyinatubaghyan baynahum fahada Allahu allatheena amanoolima ikhtalafoo feehi mina alhaqqi bi-ithnihiwallahu yahdee man yashao ila siratinmustaqeem

Mankind was [of] one religion [before their deviation]; then Allāh sent the prophets as bringers of good tidings and warners and sent down with them the Scripture in truth to judge between the people concerning that in which they differed. And none differed over it [i.e., the Scripture] except those who were given it - after the clear proofs came to them - out of jealous animosity among themselves. And Allāh guided those who believed to the truth concerning that over which they had differed, by His permission. And Allāh guides whom He wills to a straight path.

All men used to be a single ’Ummah (i.e. on a single faith). Then (after they differed in matters of faith), Allah sent prophets carrying good news and warning, and sent down with them the Book with Truth to judge between people in matters of their dispute. But it was no other than those to whom it (the Book) was given who, led by envy against each other, disputed it after the clear signs had come to them. Then Allah, by His will, guided those who believed to the truth over which they disputed; and Allah guides whom He wills to the straight path.