Sahih al-Bukhari 5707
In-book no 5707حَدَّثَنَا آدَمُ، حَدَّثَنَا شُعْبَةُ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنِ امْرَأَتِهِ، فَاطِمَةَ عَنْ أَسْمَاءَ بِنْتِ أَبِي بَكْرٍ، قَالَتْ لَعَنَ النَّبِيُّ صلى الله عليه وسلم الْوَاصِلَةَ وَالْمُسْتَوْصِلَةَ.
Narrated Asma': (the daughter of Abu Bakr) Allah's Messenger (ﷺ) has cursed such a lady as artificially lengthening (her or someone else's) hair or gets her hair lengthened.