Surah Al-Baqarah, ayah 14

2:14

وَإِذَا لَقُواْ ٱلَّذِينَ ءَامَنُواْ قَالُوٓاْ ءَامَنَّا وَإِذَا خَلَوۡاْ إِلَىٰ شَيَٰطِينِهِمۡ قَالُوٓاْ إِنَّا مَعَكُمۡ إِنَّمَا نَحۡنُ مُسۡتَهۡزِءُونَ ١٤

Wa idhā laqul-ladhīna āmanū qālū āmannā wa idhā khalaw ilā shayātīnihim qālū innā ma'akum innamā nahnu mustahzi'ūn

And when they meet those who believe, they say, "We believe"; but when they are alone with their evil ones, they say, "Indeed, we are with you; we were only mockers."