وَإِذَا لَقُوا۟ ٱلَّذِينَ ءَامَنُوا۟ قَالُوٓا۟ ءَامَنَّا وَإِذَا خَلَوْا۟ إِلَىٰ شَيَـٰطِينِهِمْ قَالُوٓا۟ إِنَّا مَعَكُمْ إِنَّمَا نَحْنُ مُسْتَهْزِءُونَ Qur’an Al-Baqara (2:14)Wai tha laqoo alla th eena a manoo q a loo a mann a wai tha khalaw il a shay at eenihim q a loo inn a maAAakum innam a na h nu mustahzioon a
Lit., "their satans" (shayatin, pl. of shaytan). In accordance with ancient Arabic usage, this term often denotes people "who, through their insolent persistence in evildoing (tamarrud), have become like satans" (Zamakhshari): an interpretation of the above verse accepted by most of the commentators. However, the term shaytan - which is derived from the verb shatana, "he was [or "became"] remote [from all that is good and true]" (Lisan al-'Arab, Taj al-'Arus) - is often used in the Qur'an to describe the "satanic" (i.e., exceedingly evil) propensities in man's own soul, and especially all impulses which run counter to truth and morality (Raghib).
A deeper phase of insincerity is actual duplicity. But it never pays in the end. If we compare such a man to a trader, he loses in the bargain.