5 : 61
وَإِذَا جَآءُوكُمۡ قَالُوٓاْ ءَامَنَّا وَقَد دَّخَلُواْ بِٱلۡكُفۡرِ وَهُمۡ قَدۡ خَرَجُواْ بِهِۦۚ وَٱللَّهُ أَعۡلَمُ بِمَا كَانُواْ يَكۡتُمُونَ
When they come to you [believers] they say, “We believe”, but in fact they are committed to disbelief both prior to their coming and after their leaving, and Allah knows best what they conceal.