Sahih al-Bukhari 5936

Arabic

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.‏

English translation

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

Reference: Sahih al-Bukhari 5936, Book of Dress. English translation by Dr. Muhammad Muhsin Khan.