Surah Al-Ma'idah, Verse 61

وَإِذَا جَآءُوكُمۡ قَالُوٓاْ ءَامَنَّا وَقَد دَّخَلُواْ بِٱلۡكُفۡرِ وَهُمۡ قَدۡ خَرَجُواْ بِهِۦۚ وَٱللَّهُ أَعۡلَمُ بِمَا كَانُواْ يَكۡتُمُونَ٦١

wa-idhā jāūkum qālū āmannā waqad dakhalū bil-kuf'ri wahum qad kharajū bihi wal-lahu aʿlamu bimā kānū yaktumūna

And when they come to you, they say, "We believe." But they have entered with disbelief [in their hearts], and they have certainly left with it. And Allāh is most knowing of what they were concealing.