Allah allows a person's thoughts and whatever occurs in his heart so long as they do not become established
حَدَّثَنَا سَعِيدُ بْنُ مَنْصُورٍ، وَقُتَيْبَةُ بْنُ سَعِيدٍ، وَمُحَمَّدُ بْنُ عُبَيْدٍ الْغُبَرِيُّ، - وَاللَّفْظُ لِسَعِيدٍ - قَالُوا حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ قَتَادَةَ، عَنْ زُرَارَةَ بْنِ أَوْفَى، عَنْ أَبِي هُرَيْرَةَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِنَّ اللَّهَ تَجَاوَزَ لأُمَّتِي مَا حَدَّثَتْ بِهِ أَنْفُسَهَا مَا لَمْ يَتَكَلَّمُوا أَوْ يَعْمَلُوا بِهِ " .
It is narrated on the authority of Abu Huraira that the Messenger of Allah (ﷺ) observed: Verily Allah forgave my people the evil promptings which arise within their hearts as long as they did not speak about them or did not act upon them.