Sahih al-Bukhari 5936
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.
حَدَّثَنَا آدَمُ، حَدَّثَنَا شُعْبَةُ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنِ امْرَأَتِهِ، فَاطِمَةَ عَنْ أَسْمَاءَ بِنْتِ أَبِي بَكْرٍ، قَالَتْ لَعَنَ النَّبِيُّ صلى الله عليه وسلم الْوَاصِلَةَ وَالْمُسْتَوْصِلَةَ‏.‏