Al-Baqarah - 2:14

وَإِذَا لَقُواْ الَّذِينَ آمَنُواْ قَالُواْ آمَنَّا وَإِذَا خَلَوْاْ إِلَى شَيَاطِينِهِمْ قَالُواْ إِنَّا مَعَكْمْ إِنَّمَا نَحْنُ مُسْتَهْزِئُونَ
[2:14]
And when they meet those who believe, they say: We believe; and when they are alone with their Shaitans, they say: Surely we are with you, we were only mocking.
When they meet those who believe, they say: "We believe;" but when they are alone with their evil ones, they say: "We are really with you: We (were) only jesting."
And when they fall in with those who believe, they say: We believe; but when they go apart to their devils they declare: Lo! we are with you; verily we did but mock.