I have a co-wife. Is there any harm for me if I give her the false impression (of getting something from my husband which he has not in fact given me)? Thereupon Messenger of Allah ﷺ said: The one who creates such a (false impression) of receiving what one has not been given is like one who wears the garment of falsehood. (Using translation from Muslim 2130a)   

أَنَّ امْرَأَةً جَاءَتْ إِلَى رَسُولِ اللهِ ﷺ فَقَالَتْ يَا رَسُولَ اللهِ إِنَّ لِي جَارَةً فَهَلْ عَلَيَّ مِنْ جُنَاحٍ أَنْ أَتَشَبَّعَ مِنْ زَوْجِي بِمَا لَمْ يُعْطِنِي؟ فَقَالَتْ قَالَ رَسُولُ اللهِ ﷺ إِنَّ الْمُتَشَبِّعَ بِمَا لَمْ يُعْطَ كَلَابِسِ ثَوْبَيْ زُورٍ  

[Machine] A woman came to the Prophet ﷺ and said, "O Messenger of Allah, is it permissible for me to say that my husband has given me something when he has not, even though I will be harmed by doing so?" The Messenger of Allah ﷺ replied, "The one who clothes himself with what he has not been given is like one who wears garments of falsehood."  

جَاءَتِ امْرَأَةٌ إِلَى النَّبِيِّ ﷺ فَقَالَتْ يَا رَسُولَ اللهِ أَيَصْلُحُ لِي أَنْ أَقُولَ أَعْطَانِي زَوْجِي وَلَمْ يُعْطِنِي إِنَّ عَلَيَّ ضَرَّةٌ؟ فَقَالَ رَسُولُ اللهِ ﷺ الْمُتَشَبِّعُ بِمَا لَمْ يُعْطَ كَلَابِسِ ثَوْبَيْ زُورٍ