It is narrated from Sayyidah Asma' bint Abi Bakr (may Allah be pleased with her) that a woman asked the Prophet (peace and blessings be upon him) and said: O Messenger of Allah! I have a fellow wife living with me - meaning a co-wife, but she disliked saying the word "co-wife" - so is there any sin on me if I make a show of being filled (well-off) with what I have not been given? The Messenger of Allah (peace and blessings be upon him) said: "Whoever pretends to be filled with what he has not been given is like one who wears two garments of falsehood."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20693