عَنْ مُعَاوِيَةَ رَضِيَ اللَّهُ عَنْهُ قَالَ سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ يَقُولُ أَيُّمَا امْرَأَةٍ أَدْخَلَتْ فِي شَعْرِهَا مِنْ شَعْرِ غَيْرِهَا فَإِنَّمَا تُدْخِلُهُ زُورًا
Narrated by Sayyiduna Muawiyah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: The woman who joins (adds) another woman's hair to her own, she introduces them only as falsehood and vanity.