Quran 3:72 — The Amramites (Ali-'Imran)

Some followers of the scripture say, "Believe in what was sent down to the believers in the morning, and reject it in the evening; maybe someday they will revert.

[3:71] O followers of the scripture, why do you confound the truth with falsehood, and conceal the truth, knowingly?

[3:73] "And do not believe except as those who follow your religion." Say, "The true guidance is GOD's guidance." If they claim that they have the same guidance, or argue with you about your Lord, say, "All grace is in GOD's hand; He bestows it upon whomever He wills." GOD is Bounteous, Omniscient.